Organic Garage is a great new store, definitely worth checking out. You'll keep coming back - I drive to Oakville from midtown Toronto to shop there. The prices are incredibly low while the quality of the produce is top-notch. It's like an old-fashioned grocery store - family-run, great personal service. The store also features a great butchershop featuring Rowe Farms meats and poultry, and some exceptional prepared foods.
For those in Toronto who do not want to travel to Oakville for very cheap and good organics, try Ambrosia on Doncaster Av at Yonge/Steeles. They have excellent products and selection presented in a "no frills" manner. And their prices reflect that as you would expect (read about their pricing policy on their website below).
I've been almost to almost every health store (but not yet Organic Garage) and I think Ambrosia's prices are the best, and may be even cheaper than the Organic Garage's (judging by the comparisons to Whole Foods on OG's website). Ambrosia also has a second location in Newmarket at Yonge/Mulock.