what about drier vent cleaning..
Local guy wants to sell me a $2500 set up on a trailer..
Generally dryer vent cleaning is not as complicated as air duct cleaning--- in air duct cleaning each house has its unique issues which can slow you down.. I think Dryer vent cleaning in more important then the Air duct cleaning because it is more likely to prevent house fires.
Most Modern well installed air duct systems can be accentually self cleaning if the owner uses higher quality filters.
For Dryer vent cleaning In many case its easier to disconnect the hose and suck out using TM and or brushes. Just be sure to unplug the dryer 1st.. some have a sensor in dryer exhaust port which can be accidently shorted out during cleaning if not careful. Most dryer vent hose runs are short and straight out the opening in the wall. The ones that are prone to Fires-- and the ones that should be cleaned and check every couple of years are the installations that have vertical hose runs and or long hose runs.
there are many 'Fly-by night" ways to clean air ducts-- Dealtimeman has it right.
In 2010 I purchased over 10k worth of air duct stuff that was going to be Truckmounted- 2 months later SF govt-- says hey you cant put that stuff across the sidewalk!

now all my air duct stuff is in the Boneyard-- waiting for me to stop procrastinating and sell the stuff.
the portable stuff is slow to work with because it can damage the customer home if you don't move slooooow.
the stuff you use with the TM-- is hackish.
Bottomline-- I don't really offer the service because it takes too long and I didn't have the guts charge enough--- Oh and It increased my asthma/allergy attacks.