Unfortunately, here in the craft-beer cesspool of Ontario, where one giant monopoly really only stocks a token amount of non-standard imports (half of which are just awful eastern European crap), sours aren't all too available, although if you don't mind spending $15 a beer or more, some bars/pubs in downtown Toronto have pretty massive beer lists with a ton of quality stuff.
The only thing remotely resembling a sour in stores here, carried year round, are the fruit lambics Mort Subite kriek and Mort Subite framboise. I really like the stuff though, and it's definitely one of my go-to-beers on my occasional trip to the liquor store. Whether Mort Subite is generally well-regarded among sour beers, I don't know, but that sour bite to these beers is absolutely fantastic, and having been a hophead pretty much since I started drinking beer, I can say I'd probably be into sours just as much - if not more - if I had more exposure to them. Lindeman's geuze was supposed to be a seasonal offering a little while back, but unfortunately it got canceled. Still, with a limited selection of beers here, probably 90% of what I buy are hoppy APAs and IPAs, Trappist beers, Mort Subite, and a TON of Unibroue's Belgian-style ales... in fact, Trois Pistoles was the first beer I ever bought for myself (having tried BMC junk, I looked for reviews on the net hoping to find something I might like)... and that single decision is what led to me being where I'm at now.