Can anyone reccomend an Air Compressor??

We have not started offering air duct cleaning yet, but have been doing some research.  I am trying to find out how much we really need to spend on an air compressor to do a good job using a TM and either one of the systems that use Whips, Brushes or both.
Can a Home Depot special for a few hundred dollars really do the trick or do we need to spend a few thousand to get a good unit that will last?  What type of air compressor do you use and how much did you spend on it?

Also what air duct cleaning system to you use if you are using a truck mount... spinning brushes, whips, anything else??

if the high pressure air doesn't move the dust then the furnace wont move it either. So the dust wont be recycled into the home so its not a worry.

spinning brushes are very good for some systems but not all. if you clean a return that uses stud chases inside walls, and the chases have wiring in them, you'll tear and tangle in the wires. best to utilize a combination of systems.

I've used many different systems over the years and the best system I've used is a negative air machine, connected to the main trunk, I use an atlantic engineering negative air machine with two motors, and dont use an air compressor at all, use air care's cobra ll brush with the hose connected to your truck mount, if you have one.  I've tested it and it will absolutely blow away any other method.  I have an abatement air compressor thats just sits in the garage that I paid 2500.00 for.  When I ran those little duct cleaning rods through ducts with the rubber agitator it just wasnt getting them clean enough for me.  If you dont have a truckmount, then I recommend air cares 4x4 vac.  It has 4 vacs and it is a very powerful machine.