I say buy the PLB and use the GPS capabilities of your phone, especially since you're in an area without a lot of tree cover. Learn how lat/lon & UTM coordinates work, carry a good gridded map, and then all you'll really need is point position from your phone's GPS. Everything beyond that is gravy.

Over time you'll become very adept and familiar with keeping up with your position on the map, helped along as needed with occasional GPS fixes. Then when you get some extra cash you'll have a bit of a clue as to features to look for in a GPS.

It's win-win. You get the immediate safety factor of a great PLB, and you then enhance your knowledge and understanding of the things that make GPS truly useful.