In reply to tony:
My experience of public auctions of bikes is that, unless you are into very old, classic bikes, the bikes on offer are generally wrecks. Often ones that the police have recovered but been unable to reunite with owners.
That's not to say you won't possibly get lucky, but you need to know what you're looking at/for.
That said, I did once go to an auction where a triathlon shop had closed down - but then word had got around and so had every other bike nut in the area, so there was a lot of competition for the good stuff.
Post edited at 10:57