The original Air Hawk cushions are available new for $129.50 from RL Motorcycles, a source recommended by the Roho Group, the Air Hawk manufacturer.
http://www.rlmotorcycles.com/cgi-bin/eShop...product=AirHawk
These are the original versions with a Neoprene bladder, not the less expensive Air Hawk 2, which has a lightweight polyurethane bladder.