The fine amount depends a lot on the country and province where you were stopped, so I can't give you an exact figure. In most of Latin America it's somewhere between 50 and 300 dollars or so, but in some places it can be quite a bit more. What is pretty universal is that they'll take points off your license or suspend your license for a while, depending on how many infractions you've accumulated and the local rules. The best thing is to check directly with your municipality or the traffic authority that gave you the ticket, because the amounts and penalties vary quite a bit.
As for GPS specifically, some places consider using it while driving falls into the same category as using your phone, others have more flexible rules if you have it mounted on the dashboard or if you have a hands-free mount. If the cop saw you holding the phone in your hand it's pretty much certain they'll fine you for that. My recommendation is that you set your route before you leave or, if you're on the highway, pull into a service station to see where you need to go. It's not worth the risk, it's dangerous and besides it ends up costing you.