Of all the used bike sales and bike auctions I've been to, this was by far the best --- and,…read moresurprisingly, the mellowest.
Need a basic used city bike for getting to class and back? CHF 150. Want something simple to leave at the train station? CHF 100. Want an almost-new commuter with a working generator and V-brakes? CHF 400. Want a nicer bike for weekend rides? Well, that's a little trickier...
Test rides are easy --- bring an ID to leave with the gatekeeper, and pop across the street for a few minutes.
Checkout couldn't be simpler (as long as you bring cash) --- each bike has the no-haggle price on a form, along with the owner's name. You take the bike to the checkout stand, pay your money, and get your receipt; the operators deal with giving the money to the seller, so you don't need to wait for them to make change. No cards accepted, though --- so bring plenty of large bills, so nobody beats you to a good bike while you're at the Bancomat.
I was looking for a good heavy-duty commuter for my wife, and a nice mountain bike for Altberg (and occasionally Üetliberg). The first one was easy --- quickly narrowed it down to a few, and picked a good one.
The mountain bike was more of a stretch --- there were a few around, but several were too large, one was too downhill-oriented (I can live without three chainrings, but do need two), and many, many were too old (I'm trading up from a late-90s steel hardtail --- I don't need another). Did eventually find a 2005 Specialized FSR that had been pressed into city duty --- it's back in the mud and woods now.