My thoughts on this is buy a small GPS that is expendable and learn to plot a position on a map and buy from demon tweaks a Don barrow Romer which is a great aid once you learn to use it £2.50 that way you can put in your own notes etc on the map as if it is only 50 miles of your house then you don't need anything hugely fancy. Also when you end somewhere that isn't on any map then you can wok out how the hell to get back to where you want to be. Also consider one with a fluxgate compass built into it to help you out.