Another scam that I've seen is this:

Me: Alright, so the price is going to be 40k
Other: Alright Deal
Me: *I put in item and wait for the other person's money*
Other: He only puts in 4000 instead of 40000 and clicks the check box
Me: I see the mistake
Other: In the meantime, he types, what are you waiting for?
Me: I say "that's only 4k not 40k
Other: No it's not! Then leaves quickly and goes offline.

I don't know if anyone else has seen this scam, but I've seen it a couple of times.