I've only sat in them briefly, and I don't really know if they are "affordable", but they look good and flexible (I like some of their multi-seat layout options).

Salamander Designs
http://salamanderdesigns.com/seating/index.jsp

If you want to see them in person, you can find them at a few places around the Bay Area (they also have a dealer locator on their website).

-Todd...