Drivers/passenger Seat Upgrade on a 1999 Shasta Sprite?

I have the same problem on my 2008 Tioga. I checked around with upholstery shops, and found the costs prohibitive. I also checked for used chairs, but they hover around $250.00 and up. The best alternative is just to get one of those plastic/fiber pads that you attack to the outside of the chairs. There are some with massage settings. Look on Ebay, they run from about $85.00 and up.