I've never bought anything real "good" from an auction site. I've seen guns in person that supposedly had the dimensions I would give to a custom stockmaker, for a gun of my own, that simply didn't fit. I'm at a loss as to why, but, it killed the sale.
I have purchased a few "lesser" guns over the net, including a 16 gauge Ithaca 37, from a private seller, that was too good to be true, a very nice gun for $225, shipped. Sometimes, you win.
But, I haven't exactly pushed my luck. I can't afford to anymore.

Best,
Ted