Try this place:

http://www.briansmodelcars.com/tutorials/tutorial.asp?TutorialID=23&CurPage=1 

Building your own is pretty easy.  Many of use here have done that using whatever was handy rather than any specific set of plans.  Use the search button to search on "paint booth", and you'll find a lot of threads on that very subject.

Andy

 Hello, Here is the booth I built

 /forums/770104/ShowPost.aspx

 Cheers

Mike