I've had to file a dispute one time with Paypal - bought a poster from a guy and it didn't show up for a month and he wasn't returning emails. Seems like Paypal is very harsh on the sellers. I got a call from the guy about 15 mins after I put in my dispute. Seems that paypal locked up his whole account and shut down all his paypal business until we got things resolved.
Have you looked at the square system? It will let you accept credit cards for a decent commission but I have no idea if you are allowed to integrate it on ebay.