Earlier this year I bought myself a nice Iwata HP-CS airbrush and with spring around the corner, I made a spray booth as well. Did some test runs with my airbrush and I was sold right away. Now, I still have a lot to learn with this new aspect of my hobby, but I feel I got off to a pretty nice start. Nothing serious worth showing yet, but I've completely disassembled a ROTF Soundwave figure and primed all parts white. Yes, white, one of the most difficult colours to handle. Maybe because it isn't a colour at all, who knows.
Anyway, below is a pic of my spray booth, which was fairly easy to make, using one I found on the internet as an example (props to the dude who came up with this basic design!)
Made from a few MDF and plexiglass panels custom sawed at the hardware store, a couple of hinges, screws, glue and a bathroom fan and flexible hose to take care of the fumes. A patch of a kitchen hood filter to finish it off. All in all about $45-$50 I'd say. The fan isn't the most powerful out there, but it will suffice for now, since I'll mainly use my airbrush and acrylics, instead of spray paints and solvent based paints.