This is the Oz DIY WB kit version 1.0, includes the sensor and display. I've got almost $500 invested in this thing and they're still selling for about that much new. Plug it into your cig lighter, screw the o2 sensor into a bung, and you've got an accurate wideband o2 setup. It uses the Bosch L1H1 5 wire sensor.

See http://techedge.com.au/vehicle/wbo2/default.htm for more info on this unit.

$300 firm