What to do with people who back out deals

Well, some people are more in a hurry than others i think. I have had pretty good luck on this forum. I do seem to remember a guy telling me his buddy wants the parts or something that I was trying to make a deal on , that was ok, i didn't give him any $$$ and i figured something else would turn up, as far as the parts..it did. patience is key, I have paid for parts that I am waiting on shipping or to pick up, I think I have three items Im waiting on now...but I figure ill hear from the folks or the box will show up...Not sure what to do if you get screwed other than make it known on the forums so no one else does.