I have never painted any for outdoor, but any indoor speakers we just request a pint of paint from the customer. We actually have a spray booth at our shop and air system left over from the car audio days of sunroofs and custom enclosure making that I use. I bought a small automotive touch up gun from harbor freight and use that. We usually keep the extra paint for the day of install and keep a small brush on the truck for touch ups and scratches. We charge 25-50 a speaker depending on the PIA factor. If you have the area to set it up like described above in other posts with everything all layed out it's really easy money.