1999 323i Engine Light / Thermostat

Engine light comes on quite a bit. Probably 4th time since I bought the car in May 2004, and never came on until December. Dealership told me that off hand he would guess the thermostat is getting "jammed". This sounds somewhat reasonable to me as the light never came on until it started to get colder.

Any idea first, is this a probable situation? second, how much will it cost to get looked at and fixed?

Third, does anyone know of a reputable BMW mechanic in NJ, preferably central jersey near the shore? I'd like to get to know one.

Thanks
LJ

Eather take it to a dealer, princeton, circle, or desemoe which ever is closest. Other then the dealers I dont know of any shops that specificaly deal with BMW or german cars. There are a few but there near Trenton.
But correct me if Im wrong but how does the check engine light come on if the thermo is open. Is there a sensor on the housing or soemthing I really dont know. Other then that how many miles are on your car? beucase it could be the o2 sensor if your car has over 100k on it. My light comes on when Im idling sometimes. And I just crossed over 100k