I'm really just in the market for a used amp but besides guitar picks, I wouldn't buy anything from Steve's.  Their prices are high and their staff are jaded 'coulda-been' musicians.  At least in Toronto that is, I've never been to the Montreal store but I've heard it's the same.
Instead I go to Moog Audio on St-Laurent on Saturdays after eating an amazing $4 breakfast and play the Moog Voyager.  This synth DESTROYS anything else I've ever touched.  It seriously sounds like it's alive.
 
 
Alliumphobia I see that you live in Montreal too, unless you're fucking with me - what's a good used music store here?  Is there anything like Songbird in Ottawa or Toronto?