eBay should get an escrow and go from there. Not hard...
And who would pay that escrow?
Since bitcoin only try to secure the seller and not the buyer they need to do a lot of extra work they dont need to think about with other payment metodes.
Make a 2 out of 3 multisig. One key to the buyer, one key to the seller, one key to the escrow.
As long as everything goes fine, the escrow doesn't really have to do anything, so he doesn't get paid. He only gets paid if there is an dispute and he has to actually do something.
I think, OpenBazar is using something like that and it makes sense.
This kind of protection is much better than chargebacks since, buyer and seller are protected. I don't get this whole "Buyer is always right" policy, from most payment processors. Buyer are also often fraudsters and make a lot of damage to merchants.