ebay and browse by distance. If you've got a particular bike in mind, set up a saved search and just see what rolls in.
Having watched a lot of bikes on ebay over the past few months, I'd suggest that if you see something you like, it's worth cheating the system and messaging the seller direct to ask if he'll accept a price to end the auction early, because if you don't, someone else will, and you'll be left wondering why the auction ended 3 days early. If they'll accept an offer to finish early and you can pay cash, then they'll accept a lower price because they won't get hit for Paypal and ebay value fees, and you can save some money.