Allen, I have the HS36 multimeter as the primary unit, the AC current clamp head ACH4, the carbon monoxide ACM3 head and in relation to this thread the air velocity and temperature head AAV3.
The multimeter was maybe 120-140 it came with the AC clamp and a bag. The AAV3 was maybe +/- $100. The carbon monoxide head was more though. I think a couple hundred. It's been awhile. There are more heads I'd like to get, just waiting for the right job to come along to need them.
I bought the units through my HVAC supplier, I think that's where they are primarily sold.

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Accurate Inspections & Consulting, Inc.
847/736-9975
Markus Keller