I hope I don't stir up too much controversy, but I've often felt that the people on this forum have been too trusting of the good intentions of others. While it's honorable to send things out based only on an IOU from the buyer, in this day and age I reserve that only for those I know well and trust, or if the dollar amounts are very small. On the flip side, I'm aware of buyers here who have paid well in advance, and have still not had their product in hand after months or longer. Again, the issue is placing too much faith in the good intentions of others. I personally wouldn't expect anyone to pay me for a product unless it was ready to ship. I don't expect others to foot the bill for my R&D. I think it speaks volumes for this community that this has taken place, but unfortunately it also means you can sometimes get burned.
I'm not suggesting by any of the above that we all resort to a policy of paranoia when dealing with others. Rather, before dealing with a person see if others have had problems. If those problems were resolved, or were due to things like death/illness in the family, then the person is probably still worth dealing with. On the other hand, if there's a long list of people who have unresolved problems, don't victimize yourself by adding to it. Caveat emptor on both sides is a good idea.
I hope you decide to remain and not leave because of a few bad apples. The larger a community grows, the more likely there will be those few who feel they can slink through the cracks without being noticed. BTW, I can't imagine anyone stiffing you for a lousy dollar. That's about as low as it gets.