You can make a foam brush system for about half the cost of the
Kleen-Rite/Air-Logic one. Go to Sam's Club and get a plastic cutting board from the restaurant section. Order solenoids, gauges, a pump, a
Flojet pump and two air regulators and screw them all to the cutting board. Find a poly tank big enough for the Hydrominder with a lid so you don't end up with an expensive insect trap hanging on the wall. The Air-Logic system is a joke - the air regulators don't need to be on a common manifold where it will take an hour to change one. I use a long nipple and an elbow for rear-mount gauges on top of the solenoid stacks for when the cheap made-in-China gauges
Kleen-Rite sells start spewing pink
soap out of the top. You'll eventually want to add a multiplex controller to shut the air supply off to the
Flojet so you don't pump a bucket of
soap down the drain when a solenoid sticks open (And make sure you have a good strainer on the pump supply).
If you don't already have a compressor, you'll need one for the
Flojet pump and to make foam. Don't waste money on an oilless one, get a decent belt-drive one.