Can you let me know how you make out? I'm having a new enclosure done this year and thinking of the bolsters. I agree that the initial price sounds excessive. Might just do it myself. How hard can it be - ss monel staples, decent fabric and only a couple of pieces that really need sewing.
I did this about 9 years ago. I replaced the foam, used the existing backing, used plain and pleated Seaquest vinyl , Seaquest piping and also the vented fabric on the bottom edge that the grommets are installed into. My bolsters curved around the back which meant that I had to cut and sew several pieces to make the turns.
I also bought a used industrial sewing machine. It really is a necessity if you have seams to sew.
I learned a few things; Having the original bolsters and taking them apart really helps cutting out the pieces.
The foam if new has to have the edges rounded over to get the correct shape and fit. I used closed cell foam and quickly learned why that stuff is so good at passing water. It also passes contact cement as if it weren't there. Spray adhesives work better.
For two bolsters, I used almost 1,000 staples. Since I stapled the material to the back and then stapled the piping over the edge, a lot of staples are needed. I used Monel staples too. They are harder to find and a more expensive than stainless.
You need a powered stapler, pneumatic or possible electric. Don't even thing about using a manual stapler
Your fingers will hurt for days from removing all the old staples and eventually pulling the new covers vinyl tight over the forms
Not counting the cost of the sewing machine, I think I spent about $300 on materials including the fairly expensive Dryfast foam but then again that was 9 years ago.
Here is a picture of the pieces that make up one bolster ( not showing the long sections.)
So, 9 years later, the bolsters are showing a bit of age, a few stains and one or two hook nicks but all in all they have held up well.
I think one key factor is that the originals as well as my replacements had the vented fabric (phiferex) on the bottom edge; that allows any moisture that gets in to drain out.
