Osprey,
Not sure of the brand of tube, but I bought them from Sos Ouch, at XStream in Seattle. He makes a back pac cataraft, and takes custom orders for catarafts as well. He also makes the nicest steelhead fishing vest I have ever seen. Spendy, but worth the bucks.

Sturgio,
What size cataraft did you get. Mine is a 10 footer with 18" tubes, and handles most anything the Cowlitz can put out. Been in some pretty nasty water with it, and just love it.