Plastic blue tarp and PVC pipes for the frames, a little rope and some duct tape is all it took for me in my garage. Plus two cheap box fans and some filters.
Not legal of course and smelly to the neighbors. Are you talkin a full on booth with supplied air, proper exhaust ventilation, with proper compliance (OSHA?NIOSH?). How many times do you intend to use it? The more times, the more money it's gonna cost and it's gonna have to be legal...don't want the Feds to come bustin in and confiscatin everything!
Owen