Cases are abundance, even in three (four?) colors, and sellers claim they can ramp up production to a few 1000/week. It's more about the nasty parts like SMIA95 camera socket, the 5MP cam module itself, the diplays and slider mech and particularly the domesheets, but at least for the latter we already explained our alternatives in feasibility study.
General rule: when we reach sales counts where supply gets short, we have sufficient volume already to create our own supply.
But yes, buying samples of all the available N900 mech parts to evaluate their quality is one usage of the complete fund. The question is if we will go and buy all the needed amount of all mech parts in advance and if we even can afford this. (the original idea been to do this when customers did final actual order and thus transfer the money to us. Only then we also know who wants a complete device and who wants the board only)


PS: We already checked all the switches and found our sourced parts to fit pretty good. We even seem to have choice of different tactile characteristics (operation force) :-)
/j