Not sure which cushions you need, but I have the back cushion for a rollover couch off my 2005 Hawk if you can use it. Only problem is I'm in Ca so you'd have to figure out how to pick it up. I'd try a marine upholstery shop first if you're looking for custom cushions.
I asked Portland friends of mine, and they've used "Lisa's Upholstery", 2000 NE 42nd St. They had the cushions on an indoor bench redone by her and were happy with the work.