@rek We buy and sell lots of kid's stuff online and I've found there to largely be two categories of people. Those who show at least basic manners and those who don't realize or care that there are other human beings sitting behind the screen. That being said, I've had the nicest interactions through second hand buys.
@rostiger i've had a lot of good interactions too :), mostly when Im the one asking for items hehe... i met a lot of rly nice ppl doing that, but i also wasnt haggling ;).