What your looking for is an isolated motor so that there is no chance of explosive fumes being drawn over an ignition source and as a secondary issue, the fans should not generate Static. (I can never remember if that means plastic blades are to be avoided - please check 1st)
If the booth is going to get constant use, you should be looking at commercially available equipment. If it will only see occassional use, there are some hobby/craft paint booths available that may be what your after. Remember that light fittings, switches and electrical sockets are also possible sources of ignition.