Normally before I sell anything, I'll do a scan-through of existing and previous ads of the same item...
Then I'll compare the prices and basically price mine according to the Mean price of what I found. This ensures that I'm not overpricing, or underpricing...
I guess as a seller, we'll always face the Houdinis (make a date to meet and test, and then inform you minutes before meeting that they found a better offer) or the Low-ballers... But I guess from forums like these, would be:
1) Picky buyers
- These people expect a brand new item, though it's 2nd hand. And they need to get real...
and...
2) Picky buyers who take the chance, any chance, to low-ball you...
- These piss me off big-time. They play around with your stuff, shake it, bite it, knock it against the wall (dun laugh, someone took an old IS lens and knocked it against a wall to "test sturdy or not")... Basically they'll play rough with your items, giving it so much punishment within the few seconds that you meet to test... And then they'll find every single minuscle fault (even paint scratched from knocking against a wall), and then tell you it's damaged... On top of that, they ask for a massive discount "because it's broken" (even though the damage is by them)...