The etrex H is a great little GPSr, but it's just that...it doesn't have any cache details on it apart from the co-ordinates. You could use your phone for reading the cache details and then use the etrex to find them.
One things though is to get the most of it you need a cable (£15), and unless you want to download co-ordinates one at a time premium membership.
Ebay is your best bet, but search about, I got my step-son one for £20