Deposits on parts

As someone who doesn't have an unlimited amount of money, I try to stay out of buying things that I don't have the money saved for. So far, I haven't been, that I can recently think of in the situation. But I have been, and I do my best to make it right. But I will say that yeah if something does come up, the seller does deserve something for holding up potential sales. So a nonrefundable deposit is reasonable, and maybe a little extra money for the time is not out of the question either. Just my 2 cents...