Read this topic if you like to know more about the risk using paypal https://bitcointalksearch.org/topic/beware-of-paypal-and-other-reversible-transfer-services-14632
Interesting problem.
I might be a newbie here but i have for example a decade old Ebay account with zero negative feedback (i guess we could find a way to verify that i'm legit that way!). I also have purchased some other stuff on this forum so i could give you the names of some forum members that can verify i don't reverse/dispute my payments.
But on a wider scale, it seems like there is a market for some kind of bitcoin insurance company