It seems that we have two separate issues:
1. Buyers that don't pay
2. Sellers that don't ship when they're paid.

I believe both are dead wrong. Are we in agreement? If you put something up for bid on Ebay, you're legally bound to ship it no matter what the final price, assuming that you have no reserve. If you buy something, no matter what the price, you're legally bound to pay.

I don't understand the friction. Why can't we all just get along?