Failed emissions... need P0107 Map Sensor. Some Questions

Today, I failed emissions with a 96 Cutlass Sierra. The faulty code was a P0107 Map/Barometric Pressure Circuit Low Input. Where is the cheapest place I could purchase one? Also, where is this sensor located? Thank you.

Where is the cheapest place I could purchase one? Also, where is this sensor located? Thank you.

Many auto stores carry emission control parts besides the dealer.
There should be a white sticker under the hood giving the location of most sensors

There should be a white sticker under the hood giving the location of most sensors

There is no sticker. Do you know the general area it may be around?