I am sure I can't give you any real help... but we needed new fabric on our cushions... went to a discount fabric outlet type of place. Found the fabric I liked at a price that wasn't out of this world. Asked the counter person if she knew anyone who did upholstering. Well, she did!
She had a little portfolio of work she had done, and we went with her. To redo both gouchos for fabric and labor it was about $600 a couple years ago. No clue what it is now.
You might do a search for foam or upholstery and see what you come up with. Awhile back there was a good thread on the original latex foam that Airstream used in 1960s... it is still available, but expensive. If you hunt you might find information that is useful in that thread.
Good luck! Post pics when you are done!
Mrs. NorCal Bambi (traveling in S Tardis ~ from the Great State of Jefferson)