I thought ild drop this in here. I bought one of these for my GS:
http://www.tramigo.net/southpacific/...2_portable.asp
Has google maps integration, links to your smart phone via an app, remote immobiliseation via a text, easy to install (I was able to DIY) and is pretty affordable at $380. Just needs a SIM (i got a $10 a month one with telstra). It also has a few features like virtual fences so if the car is moved out side of a certain area you get an alert.