I buy and sell on eBay.
Open a case on eBay. At some point, you will automatically provided with a return label (when either the seller accepts the return, or you escalate the case to eBay after the requisite # of days the seller has to work it out w/ you, which 99% of the time means 'send you a return label'.) When you ship back w/ that return label, eBay charges the cost of the return shipping to the seller's account automatically, doesn't cost you a penny.
Paypal doesn't get involved any longer, the dispute resolution process occurs within eBay (unlike years ago when item not as described complaints were handled through PayPal.)
Honest sellers have very little options against dishonest buyers. You can sell something for "parts only", and *still* be forced to give a refund if the buyer claims the item is not as advertised. Couple this with the inability to leave negative feedback against a buyer when you do get scammed, as the years progress I sell less and less on eBay, given how stacked the system is against sellers (all for the low, low commission of 13% of your item sale *AND* shipping!). For the amount I sell, one dishonest buyer can eat two or three months profit margin. As another poster indicated, most time it is easier to just let them keep the item and write it off. Fortunately, most buyers are honest folks.