inexpensive heater ducting for diesel heater?

[audiocontr]

I'm aware of the replacement ducting threads for replacing our stock gear, but im curious of ducting for the add-on multifuel heaters like the Benmar. The outside diameter is about 5 3/4" and i basically just want to grab a hose that i can bend up into the driver compartment, or throw back into the passenger. McMaster sells stuff that is half the price but good up to 250 degrees. Im still looking at about $60 for 5 feet.

Has anyone come across a cheaper alternative?

[M Wehrman]

Dryer vent hose?

[krick3tt]

Hopefully, not the plastic stuff.