It depends on what you are looking for. The problem I have with collected trees is that it will be many years before they get to the refinement stage. It is nice to work on trees that are further along. There are also trees that you are just not going to find or rarely find. Pines are a good example. Unless you are really out there looking you are not going to find many pines that are collectable and worth collecting.
...BUT, collecting could be a good way to finance your addiction. Each year collect more trees than you want so that you have stock to trade or sell later on. In a few years you could set yourself up for a zero cost hobby.