I'm just wondering if anyone here from Toronto knows of any custom shops, I haven't seen any but I know there should be a few downtown.

Custom shop just for custom paint? Try going to a normal paint shop and ask if they can reccomend you a local airbrush-er? They should know some since they'd buy their paint from there.

If that fails maybe try a car body shop, they would probably know an airbrush artist or two if they do that kind of stuff.
I wouldn't use an auto body shop. You'll get any manner of moron who hasn't a clue how the finish on a guitar should look or how to hold the body while painting it without damaging something. Plus, they won't fire up the booth for your little job. The electricity for the lights and downdraft fans would cost more than they could charge you for the job. They would likely paint it while doing a car, which means it better be the same colour as the car they're doing, or else you will see overspray from the car on your guitar. Over the years I have tried to get body shops to paint motorcycle frames, helmets, bicycle frames, etc. All ended up looking like cr@p. If you want a good job, call up Heavy Duty Cycles on Kingston Rd. (Donny Peterson's shop), and ask them who does good custom paint these days. Trust me, Donny uses only the best.