I use F&F with sellers that I have had 1 or 2 successful regular transactions.
As for selling and the 1099 the obvious problem is proving what you paid for the item. New stuff I might have a receipt but who keeps that stuff beyond the normal non-business record keeping requirements? I keep 7 years just in case the IRS tries to claim fraud in my return. No records of what I bought on eBay beyond what eBay allows me to see.