Wide angle lenses are expensive, a half decent one is going to cost you more than a new camera (I presume yours is second hand). You're also at a disadvantage because your camera's sensor is smaller, which means that a 12mm lens (which is very wide) is really a 19.2mm lens on a Rebel.
There's not much to choose from when it comes to very wide angle lenses for Canon...
Sigma 10-22mm $ (cannot be used on 5D or 1 series bodies)
Sigma 12-24mm $$
Canon 16-35mm L $$$
Canon EF-S 10-22mm $$ (cannot be used on 5D or 1 series bodies)
Canon 14mm L $$$$
Where 1 $ (very) roughly equals the price of a new Rebel body.
Maybe you should have just spent the money on a photographer who has the appropriate knowledge and experience, plus the right lens for the job.
