I went offroading and aired down my tires and when done I aired them back up with my electric air pump. It is the type that you screw onto you valve stem and plug into the cigarette lighter. Anywho, when taking it off it I stripped the threads on the valve stem and messed it up. It messed it up so I couldn't put more air in it because it would just deflate instead of inflate.
I took it in to get fixed along with some other things. The service writer quoted me $25.00 (which I thought was high) but later called me back to tell me it would be $185.00. The reason being would be due to a new "low tire sensor" replacement $67.00 labor and of course the valve stem. They essentially have to rebuild the tire he said.

So does this seem correct? Another question, does the spare tire have this sensor?

I would check Discount Tire, and see what they have to say about it.

Sounds right to me, at dealership prices of course. Yes, the spare tire has the sensor. The valve stem is part of the tire pressure sensor, so that's why you need a new one of those as well. And, they will have to remove the tire from the rim, to replace the sensor, then put it back on.

Here is a pic of the sensor.

If you took it to discount tire, and bought the sensor online, you could get it done for $70. But you'd need to program the new sensor.

Crap. The sensor don't work well anyway - I appreciate your info.

That's correct. The metal stem is actually the antenna for the sensor.
To reprogram, read the owner's manual; instructions are there; probably under tire replacement.
Just make sure you get the exact type of sensor required for the H3, GM has quite a few different sensors for different applications.