I saw this on the made in china website:
http://www.dx.com/p/mini-multi-funct...5#.UzttRsHD-Hs
You put a sim card in it from your cell phone, call it and it returns the current location. So the annual service contract is whatever you pay for the cell contract on the sim card. Your slickdeals is probably a cheaper route, but if someone has a cheap pay-as-you-go cell plan this might be better.
Also, sorry to hear your cart was stolen. It really chaps my hide how thieves feel OK just taking stuff that other people work hard for.