> You also have little recourse if a buyer rates you poorly (I guess punish him back by rating him badly too?)

Hilariously, sellers can't leave negative feedback for buyers: http://pages.ebay.com/services/forum/sellerprotection.html

If you're selling on eBay and something goes wrong (buyer claims she received a box of rocks), there really isn't much to do. PayPal and eBay favor buyers so much that if the buyer really wants her money back, she'll certainly get it.