GPS for tracking packages

Hi,
I have thought of an idea for tracking packages using GPS.My father owns a transport company and we are thinking of implementing it for our company.

Here is the idea( which i also sent to NASA design contest) with the block diagram-
**broken link removed** ... tryID=1044


Now i want to start by just interfacing a GPS(see the link above for details).So is it better to buy modules or use receiver chips?

Regards
Spelter

Tracking vehicles by GPS is commonplace, I don't see how you could do it with packages? (due to lack of satellite reception) - never mind the expense involved.

If you want to experiment you need to buy modules, building your own would probably be too difficult.

Maybe a better alternative would be to track the vehicles that are transporting the packages?