I done this under the following guidelines I set for myself: I don't want to take a chance that I will not win it (normally that I won't be at a computer at the end of auction) and I will pay the seller fair market value - even if he undervalues it. My main motivation is to win because I want or have convinced myself I need the item.

So far, I have only ever concluded my auctions on Ebay and have not yet had a seller to take me up on the request for a BIN price. Each and every time I have been told 'sorry, but I want to let the auction run...', I reply back and tell them I understand and will take my chances.

Interestingly enough, I have won some items at the end that I would've offered more for if the seller had agreed to strike a deal. Sometimes that's the way it goes, too. Ebay is funny in lots of ways. I don't over-analyze it any more than I have to these days...