If so, well, whaddya waiting for! Build your own. What you'll need is some basic tools like a drill, socket wrench, some screws (might not be necessary), a piece of wood, a donor office chair, and a car seat.
This is my chair, straight from a 1999 Chevy Tahoe from a junkyard in Brooklyn. It seemed like it was never sat in. It's super comfortable and it swivels, goes up and down, and reclines.
So, first thing is first, you need a donor office chair. Get rid (or save them for something else) the cushions. Keep the base with the wheels and pneumatic adjustment. You should also keep the screws from the base that mounts the seat bottom. Next, acquire a nice chair (try to avoid power seats. There was a really nice E39 seat I could've gotten but the power seat would've been really annoying to wire up and add weight for a battery/power supply).
Go to your local junkyard or order one online. Prices will vary depending on junkyards or online stores, but you should be able to snag a good seat for less than $100. Once you got your seat and donor, find and cut yourself a wooden board (plywood will work fine). I cut mine 14x15" IIRC. The goal is the line up the wooden board with the original screw holes of the seat. Use either the original seat bolts or acquire new ones and install the board onto the seat. Now use the donor base screws to attach the base. Make sure that you center it precisely. It might take a few tries to get the weight balance to work correctly, so experiment with that. Then you're SET. A "new" chair.
I have a couple donor office chairs and I'd love to make one out of an older Benz seat.