Correspond with them. Many of lists of spare samples that they keep for trading or sale to other members. Sometimes such spares are listed in the monthly World of Wood journal. Make sure that you keep to the conditions and payment of the member supplying you. This makes storing, shipping and handling samples far easier than random sizes.
Members can also provide a lot of advise on books on wood.
Some can even offer to sell you copies. Books on trees are as important, too. Study the trees of the area in which you live and other areas that you are likely to travel. You can decide just how much investment in equipment you care to make. The most enthusiastic end up with axes, chain saws, and even portable sawmills.