As much as I hate PayPal / eBay the fact is some of those precautions implemented are their for your safety. I can trust a top rated seller on eBay to ship me a product or know that my money is safe via Buyer's Protection but on a decentralized P2P marketplace, ratings wouldn't mean a whole lot to me. There'd be nothing stopping someone selling low items to gain feedback, gain trusted status and then pull of a major scam.
This isnt insoluble. Build it into the protocol so that when someone rates a seller their rating is multiplied times the amount of coins used in the transaction. This way positive ratings for more expensive items would be waited proportionately. As a buyer you would only buy expensive items from sellers who gradually worked their way up to being able to sell high dollar items one step at a time. When a potential buyer does a search advanced filtering options could allow them to weed out sellers who had no reputation for consistency in selling high dollar items.
There'd be a lot of liability on the owners of such a site if something like this happened.
i think you may be missing the point a little here. No one would "own" this service any more than anyone "owns" the bitcoin service.
You could do something similar to BTCJam by using a soft credit check, but again there is enormous potential for abuse since it's not a legally binding contact, so someone could just verify themselves by using someone else's identity (IE, trusted friend.) and they would both walk away with the money and there wouldn't be much legal repercussion.
the moment it is no longer an organic anarchic solution i no longer have any interest, i may as well just use ebay.
For me, a marketplace has to make me feel secure. I know that my money is recoverable if something goes wrong on eBay. If eBay don't want to co-operate I can open a dispute with my credit card provider and recover my money through there. There's literally no protection on such a marketplace you described, and if implementation of such features was introduced then imho it kind of takes away from the anonymity side.
perfectly understandable, but i feel differently, i personally do not need 100% assurance that my transaction will be smooth. i would be fine with knowing that there is a 1% chance that i will not receive my product in exchange for having a truly free market. Another way to look at it is that a company will always charge a commission even bitmit charges a very reasonable 2%. The system i describe would charge no commission so this would, atleast to some degree, offset the fact that transactions could not be insured.