I calculated it out and assuming a gain of 10mpg it would take around 23,000 miles of driving for a $300 sensor to break even. So I guess ill keep looking and hoping to find one cheaper because I don't think the gain is worth the cost at this point.
Do you know that the L2H2 will not work?
To monitor lean burn I bought a lcd display voltmeter off ebay for about $12. Then I followed the instructions here:
http://www.gassavers.org/showthread.php?t=2427
The ecu is at the bottom right under the dash of the passenger seat. So I ran a couple wires from the spot in the dash I mounted the lcd to the ecu, and spliced into:
"Positive lead of the DMM/DVM to pin D14 (orange with blue stripe)
Negative lead to pin D16 (blue with green stripe wire)"
Then I found that the lcd meter I bought cannot power itself from the car battery like I was hoping because its ultimately measuring voltage from the car battery so its causes problems and actually threw a check engine light. I had it powering off the "clock" spot that my car did not have. Suprisingly enough when removing that dummy plate where the clock goes I had a 12v source. Anyway I ran another 2 wires down to the passenger floorboard which is currently hooked into one of those larger block 6v flashlight battery. Since its a seperate power source it works.
I plan on installing a switch on the dash next to the lcd so I can easily turn it on and off. Then putting aligator clips on the wires going to the battery so its easy to replace. Also I think the battery could be concealed in the center column behind the cigarette lighter piece so I might stick it in there so its out of sight.