One thing to consider is some of the auction sites do not have a clue about firearms or anything they are selling, thus communication is paramount.
I have never liked "Sold as is"
However, in purchasing something that is to be sold as is, credit card (CC) would be my prefered method. With a CC you have some protection & can dispute the charge.
I always like dealers that offer returns within 3 or so days if not satisfied. However, you do pay to ship it back. I have always liked Auction Arms because sellers must offer a return period or they are not welcome.
Appreciate the warning.