As you say no one has reasonably said how a third party person holding funds would be able to make this deal work. I don't quite know what you are saying about the buyer denies receiving funds and I could be scammed can you elaborate?
corrected myself here:
So, the contract is signed, funds are sent afterwards vs. contract signed, no funds sent. Will the blockchain be sufficient as evidence that no payment was made?
Actually OP, I come to think that YOU would be the beneficent of an escrow service.
1) Auction ends
2) funds are transferred to escrow
3) deal is made perfect
4) funds are forwarded to you.
5)
?6) Profit
An escrow service would actually be useful for you in case your customer wouldn't pay and you'd have a hard time proving legally that no payment was made.
I'd not discard it from the beginning.
Also again, don't get pissed so easily. On this forums, everyone is a scammer until proven otherwise. It lies in the nature of a non-reversible transaction system and is not an insult to you personally so you really shouldn't take it personally.