Guide for the purchase of yamadori and trees in general
If one wishes to get the most out of the investment, buying a bonsai can be complicated. There will always be that doubt as to whether the tree that we're being offered is really worth the price being asked.
In the case of trees that need work everything gets even more complicated as decisive factors come into play, such as the size of the root mass, the vigour of the tree and of course the likelihood that the tree in question will become a good bonsai.
I'm going to try to explain what should, according to my criteria, be looked for in a good prebonsai (yamadori or not) and what is valued.
Here is some advice:
Don't pay for the future at the price of the present
This means that we shouldn't pay for what the tree may one day become, but for what it is right now. For example, one doesn't pay for a diamond stone at the same price as one that has been cut and encrusted into a ring designed by a famous artist.
It's quite true that a tree that has great potential will be more expensive than one that doesn't, this goes without saying, but never to the point at which we are charged the price that the tree will have once it has been repotted, styled and cultivated for four years.
It's very common, when presented with a yamadori which is planted in a huge wooden box that the salesman will say that famous phrase - "as soon as it's been repotted and styled a bit it will be ….. (usually something synonymous with the best bonsai ever)". And, OK, we may agree, but that first repotting to a bonsai pot can be very risky (especially in conifers) and it will also be impossible to style the tree for at least a year, which is the time that a pine or any other conifer needs to recover. Conclusion: the time that we will need to invest and the risk that will have to be taken should not be ignored and should be valued when the purchase is being considered.
But the opposite is also the case, we shouldn't be surprised when we are quoted a higher price for a tree which is in an adequately sized bonsai pot, which has been left to recuperate for at least one season and which has abundant branches to work with.
If the seller ran the risk and took the time for us so that we may enjoy material "ready for consumption", it's logical that this 'potensai' (potential bonsai) should be more expensive than one which is still in its early stages.
Don't underestimate the risk that is taken by buying a weak or ill plant
This is another one of those things that many enthusiasts don't take into account. It just may happen that we are offered a tree which we really like a lot and which we'd love to work on to see just how beautiful it will be once we've let lose our creativity, demonstrated our talent for wiring, for branch bending, for repotting… and who knows what else. But, what a shame!, it's a bit yellow, or the buds are tiny, or this years shoots can hardly be seen, or to put it another way the tree which captured our attention is sick or weak.
It would be sensible not to buy it as, depending on the case in hand, we may be risking 100% of our investment.
Experience tells me that an enthusiast who has taken a liking for a tree is not capable of resisting the temptation to style it no matter how weak it may be.
In other words, don't fantasise about the fact that you're going to leave the tree to recover its strength until you style it. Hardly anybody is capable of putting up with such a long wait with the temptation living in their own home. What's more is that this time is money, as is the risk that you've taken by buying a plant in bad health.
I insist, don't buy a plant in bad condition but, if you do, the price should be good enough to justify the risk.
Fortunate are those that find a trustworthy supplier
Please, may nobody be offended. What I mean to say is that it's good to have a regular supplier, a supplier who has proved over the course of a few years that they are worthy of our trust.
I know of a case of someone that sold a yew which was planted in a big pot, a pot which hid a great surprise - the trunk had been cut just above the roots, it was a tree without roots.
Of course the tree died in the client's home but, imagine his surprise when he took it out of the pot and discovered what had happened, that he'd been sold a huge cutting for the price of a tree. Fortunately this was an isolated case and warning doesn't have to be made of this practice.
A good supplier is one that not only offers well cultivated trees, but that is also familiar with our technical and artistic level, who knows our talents for cultivation (or lack thereof), and who can advise in the selection of the most suitable material for our profile. If he is also able to help in the design and is capable of giving ideas of a high level for the styling of the future bonsai then we've found the ideal supplier.
A tree doesn't have to be more expensive for having been collected (yamadori)
Sometimes, plants are collected which should never have been collected due to their lack of interest as bonsai, but on the other hand high quantities of money are asked due to the simple fact that they are yamadori.
In general yamadori possess qualities which are not present in trees which haven't been collected from nature, but this is only the case when the collector is sufficiently sensible. The conclusion should be that the price of a tree is directly proportionate to the qualities it possesses, independently of its origin.
What is valued in a prebonsai?
Stage of cultivation
The more years that a tree has undergone well directed cultivation, the better will be its characteristics and the higher its price.
Stage of education of the roots
This is one of the key points. It's not the same to buy a pine in a big wooden box as to buy it in a bonsai pot in proportion with its size. The transplant from the wooden box to the definitive bonsai pot may mean, in many cases, many long years of cultivation and risks taken by the cultivator. This also has its price.
If you are going to buy a yamadori and you can see that the base of the trunk is right at the edge of the pot or box that it's planted in, don't think that this was the desire of a capricious collector but rather that it has all the roots on one side and that it's also probable that it has one big tap root that goes from the trunk to the other side of the box. The transplant of this tree to the definitive box will probably take a minimum of two transplants (4-5 years).
And let's be reasonable, if the yamadori that you're going to buy is in the definitive pot it probably means that the person responsible has taken 4-5 years (in most cases) to put it there and all that work has to be paid for.
The texture of the bark and the wood
There are those that seem to value bonsais according to their weight, only paying attention to the size and thickness of the tree.
On the other hand, enthusiasts who have been trained well are able to appreciate other, perhaps less evident qualities, qualities which are the ingredient which give the tree that something special which differentiate it from all the others.
When one is able to distinguish the textures which show age in a tree, it's an unmistakable sign that he or she has taken a step further in their training as a bonsaist.
The price of a tree can shoot up due to the quality of its bark or due to the fact that its dead wood has that cracked texture which is only possessed by centuries old wood. The textures denote the age and in Japan this particularity is taken as one of the principal differentiating factors.
Proportion and movement
We all know this, a bonsai or prebonsai should have harmonious proportions and interesting movement.
Good conicity and a well formed nebari are also highly valued, although, sometimes, and depending on each species, a blind eye can be turned if the tree doesn't have a textbook nebari if this defect is compensated by the character and authenticity which some yamadori can possess.
Branching
Another aspect which is often passed by when a tree is being valued, Branching may take years of cultivation and we all know that time is money.
Although not everyone knows which branching costs money and which doesn't. What should be asked of a prebonsai in this sense is the following:
First: there should be a lot of healthy branches. Second: The branches should be heavily subdivided, that is to say that they are heavily branched. A tree with a lot of primary branches can seem to be very dense, and therefore ideal, but that may not be the case. A bonsai is formed using just enough primary branches, but these should be very branched themselves (secondary, tertiary…branches). Third: This is the most important point. The vegetation should start as close as possible to the base of the branch and continue to the end. Only in this way will it be possible to reduce the size of the crown. For these reasons a tree with good (high quality) branching will be more expensive than one whose branching is not so good, or which is totally lacking.
Species
Some species are fashionable (offer and demand), others are difficult to root, others are rare and others imported. There are those which naturally possess interesting shapes and others whose growth profile is totally anti-bonsai. There are those with small leaves and those whose leaves cannot be reduced in size. There is a whole world of species and qualities and so a world of prices.
Pot
Who hasn't heard talk of Tokoname pots? These are supposedly the highest quality pots and, therefore, the most expensive, sometimes even being worth much more than the tree which they contain.
At the other extreme are recycled containers and in between infinite possibilities. Depending on the pot/container in which the tree that you want to buy has been placed its price will have been more or less affected.
I'm putting this down to experience, and often look at as an opportunity to restyle 
and try new techniques, ... and try to remember next time to look for the less obvious faults before purchase. 
The more you learn, the more there is to learn 
found this and thought Id bump it as its a great read for those of us who are new to bonsai
thankyou for the bump, had totally missed it!
