Darren Addy
EF5
While I was being somewhat tongue in cheek suggesting you buy a - gasp! - film camera, the idea will work!
Absolutely. The trick is finding a real wide angle to use on that film body without spending a fortune. You don't even have to give up autofocus, if you don't want to: One really budget way would be to get a Pentax MZ or ZX film body. They are ugly-as-all-get-out IMHO, but cheap. If you can find one with a FA-J 18-35mm, so much the better. (At the wide end, this would be just about equiv. to a 11mm on a Canon 1.6x crop). Otherwise, buy it new for $149.
Ultra-wide rectilinear on a budget using **gasp** film.
(Within the past month, somebody sold a Pentax digital *istD with the FA-J 18-35mm for $250. I'd pull the lens to use it on a film body and put a Pentax-A lens on the *istD.)
Otherwise, your challenge is to find a wide wide that doesn't require you to sell a kidney to purchase. (For example, Canon made a FD 14mm lens and one is on ebay right now for $2000. Tamron 14mm f2.8 has a Buy It Now of $699.
I believe the widest full frame rectilinear you can get right now is the Sigma 12-24mm. One went for just under $400 last month, but it will usually run you more like $500. The beauty of that lens is, you can shoot it on a film camera or a digital. (It would be an 18-36mm equiv. on a APS-C sensor... and you could still use it if you got a full-frame digital and get your ultrawide coverage again.)
In any event, if you are going the film camera route... get the lens first (not caring what mount it is) and then get a film body of that mount to match.