If you like it.. go get one.. Think of it as an investment into you getting outside, fresh air and enjoying nature.
We have friends that are steadily going to things like amusement parks, movies, etc ALL the time to entertain their kids.
We spent a portion on what they spend and bought a nice gps. The kids are loving these trips and we love the idea of them getting fresh air, exercise and seeing places and things they would not have seen otherwise.
Way we see it, 20 years from now the kids wont remember what movie they saw but they will remember these adventures.
Check out the classifieds here, get a nice used one. We tried a few without the GPS and found the first one pretty easy with google maps (it was in the woods and required bushwaccking , but some of the hints gave the location area away) Others were a little harder.