Yea, you are probably right about that. I simply copied a previous Yubikey auction here, to be honest.
So I think 50% of new-price (29.99 USD) in BTC is probably a fair starting bid. What do you think?
Yes - according to Mt.Gox they only work with Mt.Gox - they also offer "unbranded ones", but I don't know if there is a way around then or how they are technically locked to Mt.Gox.