Notice I wrote I have safeguards in place. I don't have a checking account linked and I'll cancel the CC on file so they can't dip into that either. PayPal isn't a lending institution so they have no real power to collect, but they can threaten. I'll just contest the debt as not valid, but I seriously doubt they'll sic collections on me in an obvious case of a bad buyer (which I'll have evidence of to file a counterclaim).
What I described has happened to some very long time reputable sellers on eBay. It's sad but true although not common. If you sell many items over many years chances are you will get ripped off at some point but that is the cost of doing business like any business. This isn't a reason to quit selling on eBay but just to know it can happen. I only say this from my own experience and many others. I was really shocked that you don't really have the protection as a seller that they say you do. A buyer on the other hand...