Someone I know bought a HP Phone/PDA from eBay for $300. It's locked as a cellphone, so he can't use it yet in that capacity, but he uses the unit as a GPS. I don't understand how it works exactly, I always thought you had to pay a monthly fee, or a one time purchase fee, and then for each additional map, you had to pay.
Since his unit is still locked, he doesn't have any data plans associated with it. I think the GPS software came pre-installed, but he was showing me it was following his every move...we were on a commuter train, and it followed his path. How was it able to track us if it didn't have any native data support (maybe it was doing it through wifi, but in the area's the trains chugs along, I can't see how any consistant signal would reach us, let alone let us connect). He said the PDA has a GPS reciever - but what is he connecting to?