Surely, I opened my mouth too early, you offered "a couple hundred bucks" - I said $250 would be sufficient, I clicked "send" and then thought - "Oh crap! wait... a minute..." and followed up telling you $250 is unreasonable.
So you offered to sell them the domain for $250 and they accepted your offer. I feel like you're not telling us the whole story, and "they're trying to stiff me" doesn't seem accurate at all.
They offered a couple hundred bucks and he thought fine, $250. Then he realized the pagerank, publicity, link backs, and worth of the domain far exceeded $250 after he sent the message. That's probably what he isn't telling us.
Surely, I opened my mouth too early, you offered "a couple hundred bucks" - I said $250 would be sufficient, I clicked "send" and then thought - "Oh crap! wait... a minute..." and followed up telling you $250 is unreasonable.