Paul,
Two things I might add:
1. The designation "instrument" grade or "luthier" grade get tossed around a lot, and often with not much precision. I have tried researching the official grading rules for these designations withour much real success. When paying the prices commanded by the real thing - and you WILL know it when you see it - I find is important to at least see photos of both entire sides of the pieces offered,and in addition to reason out or visualize in your own mind what intermediate slices would probalby look like because one rarely uses the face as is.
2. My experience after chasing really top level wood for many years is that it is difficult, and can be very expensive, to try to find wood at the time you need it. The most beautful pieces of wood that I have bought over the years were purchased because they were extraordinary and I knew I would likely not see them again, not because I had a project at hand at the time that needed them, Havng said that, the projects seem to have eventually come along because while most of my stock probably sits an average of five years of so, it does eventually become the "perfect" piece for something I am building, or I choose to build to capitalize on the appearance of a particular piece.
Karl
Karl