A friend of mine from a club I was in previously, came up with this home made booth which is inexpensive and works well.

Parts you will need.

Large plastic storage tub (Cheap at most stores)
Window fan (with a sealed motor, very common)
Airconditioner filter
Scrap cardboard
Duct tape

Cut a section out of the bottom of the tub large enough to tape AC filter.
Tape fan behind the AC filter and cover area of fan with cardboard so all air the fan pulls, is through the box..

Now take more cardboard and make "wings" on the outside of the plastic box to fit and seal your windows.

The AC filter will keep over spray off the window screens. be SURE you use a sealed fan if you use oil based paints to keep down fire hazard.

Absolutely - that's what I did.
I just used a computer fan instead (had a spare sitting around)
Gallery of images

Scott:

How much air does the computer fan pull through the filter? Does it get the air clear in the spray area, and do you have any residual fumes in the room? This is a good idea. I had thought about putting one under the spray area, and one in the back, pulling through a filter, and exhausting from a chamber (pushing) through a connection hose out a window or such.

Matt

I used a pretty big fan and it does a decent job of moving the air. The beauty of this method is I can always add another fan next to it or on the other side/top.