I'm not sure exactly where you're located, Spot, but on the northeast end of Fort Worth is a place that sells the hose by the foot. I walked out of there $6 light, but with the ducting. I forget their name exactly at the moment, but could dredge it up I'm sure. Something like Classic Auto Air. They specialize in installing under-dash air conditioners in classic vehicles. They also happen to have duct hose by the foot that worked for me.
Bill