You could try using the standard mapping apps like Apple Maps and Google Maps. MEdwards is correct, both of these apps need a connection either through wifi or cellular data as they use real time mapping information. I've even heard of pilots in larger certified aircraft using this method in a pinch. As long as there is cell signal where you are flying, I don't see why you couldn't do this.

If you wanted actual GPS and were looking to keep costs down, fltplan go looks like it could be a candidate. Couple that with an inexpensive Bluetooth GPS receiver like the Garmin GLO or similar model from Dual and you'd be set. You can get receivers like these for less than $100 new ($80 or less used if you look in the right places).