Yeah, that $50 was a few years ago. The point was that you need to figure out a reasonable hourly, daily, half day charge for the booth rental. You don't want to go too high so that the damn thing sits there unused for hours or days at a time but you also don't want to go too low so that you don't make any money.

The filters I was refering to was the one that are in the booth itself...usually in the doors and the back wall in front of the fans to filter out all of the birds and dust in the air.

I think it's a pretty good niche for a business. Lots of people want to squirt their own cars or bikes. Even if it's just a fender or a hood. All you have to do is supply a dust free booth with good air that is free of water and oil and take in the money. Paint runs and poor prep or masking are none of your concern. I'd even make them bring their own spray gun so there could be no bitching about that. Just supply the atmosphere and leave the rest to the customer. Oh, and take away their cigarettes at the door.