Otherwise, all the other parts could be made from scratch in a local millwork shop. I'm not sure what would need steam bending besides those inside ribs, but steam bending is not that highly technical.
As for a used replacement, Google is your friend, but it may take a while. I own several boats which have turned out to be rare and unreplaceable. Just have to keep fixing them.
Full Size Sail Rig
First Need Purifier
The Kayak Wing
Paddler's Truck Rack