At some point I'll want to be buying in the West Midlands and auctions are sure to be one option.

Googling has come up with:

Andrew Grant
Cottons
Howkins Harrison

Any more?

Just joined HPC so only now read your request. I know the area quite well but need to know what sort of property that you are looking for. i.e. rural, suburban, inner city ?

Of those that you have mentioned Andrew Grant is a large multi-office concern selling all sorts but plenty of up-market properties. Howkins & Harrison tend to be more rural and sell quite a few farms and country property. Cottons is more suburban I think. My knowledge is more the rural market and could tell you of lots more agents who sell at auction.