My DW and I have been caching for 2 1/2 years and enjoy it quite a bit. We just purchased a Magellan eXplorist 210 for around $160 and feel it's a good choice. Some of the less expensive models don't allow waypoints to be downloaded to them from the geocaching.com site, meaning you have to put the cache information into the GPS unit by hand. We did that for quite a while and it gets tiring, especially when you're entering more than a couple. It can also cause errors in coordinates, etc. The Garmin Legend is a popular unit for about the same price. The main differences between the $150 units and the $250-$500 units are a color screen instead of B/W and possibly more detailed maps built into the unit. Our 210 has quite a bit of memory for us to download more detailed maps and quite a bit of memory for waypoints, more memory than a lot of the more expensive units. It also comes with a free USB cable for connecting the unit to a PC for waypoint downloads. Not all models include the cable, which can cost another $25 or more. The GPS Store.com has pretty good prices as do other places on the Net. If your DD decides to do this, shop around on the Net for prices. Shipping usually runs around $6.50 or so per unit. It may seem like a big initial investment but a decent GPS unit will bring many hours of enjoyment to someone who enjoys geocaching!
Mike (alias "Team SAR-Dogs" on the geocaching.com site)