the utrak system is being revised again ( I know the fellow designing it VERY well.) when its done you can track the vehicle in real time via GPRS.
two things to consider here - you asked for cheap and good in the same phrase.
if that is the case then its not going to happen,
for GSM paging - GiSMo + mongoose M80G
if the car is sneezed on you will know. I can get the GSM unit custom programmed to tell you EXACTLY what has been tripped on you car of if it is being towed.
total bill $1350.
have done 3 like this now and it makes for some piece of mind.