I got a used bike here for my 9-day vacation in montreal. only costs me $60, yes it's a shitty old rusty bike, but it's functional. much cheaper than renting one for $20-30 a day. also with bike theft such a problem in this city, you dont' want to leave a nice rental bike outside for more than a few minutes, I saw so many bikes locked on the street with seatpost or a wheel missing.
Also this is not just a used bike store, they sell nice new bikes and accessories as well.