That's one trade I would love to learn more. My dad bought an upholstry staple gun so he could do most of his stuff himself. The best place to learn how to do something: Youtube. Just type in "upholstery" and you'll be a minute or two from learning how to do what you want to do. Just need to find some seat foam or an old piece of furniture that you can steal some from. I know a place that does a great job so I'm hoping they haven't raised their prices in the last year since I talked to them. I would like to see some Benly specific pics of some seat work though.
All in good time.