The Global Real Time Portable Mini GMS/GPS/GPRS Tracker is low cost unit.
There is no monthly service required.
It does need a SIM card to work either ATT or T-mobile.
It works by sending the target GPS information back to a user over the cell network.
Battery life for the device is 3-4 days if not wired into a power source.
There are many cellphone Apps and computer programs that will display the target GPS information in real time on a Google Map interface.
This is a cool device for someone who is good with technology and and doesn’t mind the setup.
For someone who is not technically inclined a subscription plan is always a options. Read here for other options.