Aluminum flexible expandable duct

New Aluminum flexible expandable duct:
(a) 6″ diameter x 3 ft long- stretched out to 10 ft @ $60.00
(b) 7″ diameter x 3 ft long- stretched out to 10 ft @ $70.00
(c) 8″ diameter x 3 ft long- stretched out to 10 ft @ $90.00
thanks!