I sold an iPad on eBay about a year ago, and on top of being charged close to 20% of selling price by eBay AND PayPal, I did not get my money for almost 3 months after the purchase. The chick who bought the iPad has recently moved, but did not update her shipping address on either PayPal or eBay sites, until 2 days after I shipped the iPad to her. Sent me a nastygram calling me names, disputed PayPal transaction, reported me to eBay Safe Harbor for fraud.... What saved me, is a habit of taking screenshots of interactions with buyers/sellers on eBay, because it has previously saved my ass couple of times before.
Anyway, after almost 3 months I managed to get my money from PayPal. After that I got an email from that stupid chick promising to file a "class action lawsuit" against me. Haven't heard from her since.