One thing that holds me back from bidding a higher amount when I see a listing for something that I want is that when the auction ends days or weeks from now, there is a significant risk from an appreciating bitcoin.

In other words, I simply don't know what my bitcoins will be worth come the day when the auction completes.

This past week, with the BTC/USD seeing an increase of more than 10%, is a perfect example.

Since I cannot retract my bid if the rate fluctuates, had I placed a bid that bid amount effectively increased 10% over what I originally had intended it to be.

I don't know which is greater ... the problem (for buyers) or the opportunity (for sellers, when BTC/USD appreciates).

Perhaps there is an alternate auction format to allow this?  For example, if I as a seller had the ability to choose the currency for a listing, yet still able to specify that the winning bidder pays with bitcoin, this might no longer be as much of a problem.