I haven't installed mine yet, but sicksubie put a set into his car. He has a thread on the topic
here.
I picked mine up locally as a trade for a digital camera. It worked out to about $270.
Higher end seats... Not too sure, and would almost certainly be more work. At the end of the day I'm sure you could make nearly any set of seats fit into the car, but where does the result become worth the effort?