I've been trolling the boards for several months and enjoy reading the posts. My boss just reupholstered my seat 3 weeks ago. Very cheap, under 150 dollars. They replaced all the foam as well and let me tell you my butt appreciates it.
They recovered it in pleather or something. I guess it really depends on what condition your seat is in but if it's a matter of worn cushioning and cover then this might be an ideal option.