Installing GPS on a laptop, you need two things: the map software and a GPS receiver. There are basically two types of GPS receivers, one type is the receiver only, they are cheaper, but they do not work alone. They have to be connected to a laptop. The other type can also be used without laptop (but a little more expensive.) I would suggest you buy the later one because of the flexibility. No GPS receiver needs to subscribe any service. They just receive signals from the sky - a free ride on US satellite system.
We were discussing about the software, Garmin, Magillan, etc. have their own map software but there are many other better ones, such as MS Streets & Trips, Tom Tom, etc. I like Routis better from my test results.
GPS receivers cost about $60 - $200, software cost from $8 - $500 depending where you get them.