Ken,

It takes a little bit of planning, but it should cost you nothing. GPS is free.

As DanS said above Google Maps will allow you to download the maps and you are off in running.

For example: when we are on Rhine cruise the ship had WiFi. So when we pulled into a town and on the ship I would download the maps and locate where we I was at that moment. The rest of the day my phone was in airplane mode and I google maps could always tell me where I was and where I was headed.

I will ask my travel friends what app they used. There is an offline GPS app they used.

Will get back with you.