If you're looking to do this, I have some advice. A dive shop opened up in my home town, and there is NOT a lot of scuba diving to be had here. One lesson they learned quickly (opened in April 2011, moved in Dec 2011) was that it's REALLY about location. They're spending extra cash on a better location, and it's working. Another thing, making it a community instead of a business makes the business better...when they moved, they had about a dozen people volunteering tons of time. I volunteered 60 hours of work in a little over 3 days...and that's because I found out about the move late AND I had to still go to college. Speaking of college: depending on your location (I'm guessing you're in Montreal, "Son of Cold") you might want to set up a shop near a college campus and see if you can't contract out work with a scuba club in that campus. Our Scuba Club has recently started the process to get that paperwork drawn up.
And the last thing is: volunteerism. My LDS is setting people up on internships and paying us back in certifications, gear discounts, etc. They can't afford to make the LDS their full-time job, and they can't afford to pay us as employees (oh yeah, I now work there)....so we barter. Great for all of us. They're getting me certs and I'm buying gear because I'm becoming more involved. I helped them move, I've helped them grow, I've done advertising runs all through the city....I really feel connected with the LDS, and they're quickly becoming a large part of the town. More and more people know about it and are getting interested. Few divers around here aren't aware of the shop.