Camera Metering System

Where can I buy a telescopic mast (about 10 meters) for under $500?

I need to buy a telescopic mast as used by some amateur radio guys or as used by professional photographs to do elevated photography. The mast that I found on the internet are complete systems ready-to-go suitable for elevated photography and they cost around $5k. I can DIY my own camera pan/tilt head and only need to find a telescopic mast. An air-operated one would be a plus. Thanks.

www.hilomast.com based in florida

Nikon’s Metering System