Earlier quoted context omitted.
eBay is already tremendously hostile to sellers before the fees. Can't leave feedback for buyers, a refund policy via PayPal that seems tailor made to allow scam buyers to get free stuff, and so forth. Basically it seems like the only thing a buyer can be sanctioned for is simple non-payment.
Also ebay's huge fees make it almost not worth bothering to sell on there.
The "referral fee" ranges from 8%, to 15% (common), and up. Up can go pretty high, but mostly for Amazon's own stuff.
Ebay's are mostly just in the 10% range: http://pages.ebay.com/help/sell/fees.html