GPS data is available for free; most commercial software that uses it is simply adding an interface and charging through the nose for it.
If you don't mind a little bit of programming, or (perhaps worse) fraternising with programmers, Link hidden: Login to view
is a free and open source, and designed specifically to keep programming requirements to a minimum. If that's too much for now, you might just stick to Android-powered tablets and phones and use one of the many GPS apps that are available for Android (some are reviewed Link hidden: Login to view
Really, getting familiarised with one or more apps, then installing them for a slight premium, maybe even writing a we-speeky-English PDF guide for the app to save average users from drowning in information overload, could be a very good hook for your sales pitch. Many years ago I did this with burned copies of OpenCD; since the CD itself was free for anyone to download, I sold the CD, plus a concise guide to each of the programs on it, for $30 at flea markets. Sold piles of them at that price, because consumers love hi-tech, except the part where they have to learn how it works. Taking an approach along those lines to the GPS market could possibly make you quite a few sales.