eBay feedback

I bid on a camera on eBay and got it for a good price. Then the seller said he wanted to cancel the transaction because he had sold it on craigslist. Then he said that fell through (meaning he had the camera all along but thought he was getting more money for it). Then he said it had been sold. So I left him negative feedback which he's complaining about. He also said I'd responded to his craigslist listing which was for more money, after he finally said it had been sold.

He says because he wasn't rude to me I shouldn't leave negative feedback. I say that if you put something up for auction you commit to sell it for the final bid and don't back out it you think you can get a better price elsewhere.

Am I being a prick?