Complete newbie here, I've never really looked into a GPS unit, but my wife and I do like to go out hiking and snowshoeing so I've often thought about it. Generally speaking we stick to paths and places we know but this idea of Geocaching seems like a great thing to do. (An old friend we met at a wedding got us thinking about this last weekend as she apparently is pretty active doing this)
That being said, we have 2 two young children so money isn't easy to come by.
Realistically, what should we expect to spend for a GPS unit, and are there other expenses we should expect to incur (software etc)?