Ebay has a lot of portable China Spray booths that run from $1000 to $2000. Most are a little more than inflatable bounce things.
The one at the SEMA is manufactured in Texas by Mobile Environmental Solutions. Single booth 23' x15' was $9995.00 and twin booth 23' x 48' was $19995. They seem to be made of material similar to those auto paint shop curtains that divide up shop areas. According to them, the booth is made of materials that pass NFPA (National Fire Protection Association)701 test methods 1 &2. TV's Garage Squad show is shown using their booths. But I would check with your local fire department
first before purchasing one.