O2 sensor

[John]

Hi S-ER Fans:

I own and drive a 1996 Infiniti G-20. Recently, my Infiniti's "check engine"
light came on, and a highly recommended, rather high priced mechanic
charged me $36 to tell me that the light was an indication that my O2
sensor had gone bad. The mechanic further offered to replace the sensor
for $180 parts/$65 labor.

A look under my G-20's hood revealed the sensor, which I removed and
cleaned, hoping to restore my sensor rather than replace it. I figure if I
re-set (turn off) the "check engine" light and it stays off, I successfully
restored my O2 sensor. If I re-set the light and it comes back on, then I
figure that I need to replace the sensor.

Now, I have a couple of questions:
1. Can you tell me how to re-set the "check engine" light?
2. Do you know any aftermarket sources of O2 sensors where I can find
one for a less than the $180 (ouch!) "deal" offered to me by the mechanic?

Thanks, and have a great day! John