You can use GPS itself for free as that is paid for by tax dollars. And if you can use latitude and longitude readings by themselves, you are good to go.
For all map applications, email and Internet, you need a BB data plan. Some have managed to get Internet via WiFi without a BB data plan, but that is a very poor work around. To get all the value of a BB, you need the BB data plan. If you can't afford it, then maybe it isn't the right device for you.