These look like they might be adaptable.
http://www.pcrange.biz/index.php?page=p_rheobus35&id=1
The name Rheobus suggests that the knobs are potentiometers (rheostats). If so, strip out most of the circuitry, add a CORE and an AIN, and you’ve got a nice-looking backlit four knob controller for your PC.
BTW the price is in Australian dollars, so it’s about $20 US.