I didn't know these had gotten to be so cheap. I ordered one from Summit today to see if it'll help me get my 'pane setup tuned up right. Total cost was $70.80. Pretty cheap if it works as I expect.
SUM-G2986 A/F GAUGE ONLY BAR GRAPH
SUM-G2989 STANDARD O2 SENSOR
SUM-G2990 O2 SENSOR BUNG WELD-IN
It's a panel-mount 2-1/16" rich/lean air/fuel mixture indicator, low-end (no heat) O2 sensor, and a metric weld bung for the exhaust pipe.
I was gonna build my own indicator using a generic 02 sensor -- cause I was thinking the a/f mixture gauges were still a couple hundred bucks like they used to be. Glad I found this first.