I have a Garmin eTrex, under $100, works great for geocaching. Check eBay and Craigslist and you can find reconditioned ones or used ones from folks who have upgraded to fancier ones. Just be careful, geocaching can be addictive and it can get expensive....if you like it, you decide you need a fancier gps'r, then you decide you need a Jeep so you can drive to some of the more difficult caches, then you need a kayak so you can get to the ones on islands, then you need a motorhome so you can take all that stuff and go on geocaching RV trips..........
Smart phones work great for geocaching until you get out of cell range and then, if you don't have a handheld gps'r, you're out-of-luck. We cache with the Garmin Nuvi in the car that gets to the general area, then we use the phone and/or the eTrex to get right to the cache.
Geocaching will take you places you never would have gone otherwise. Enjoy it !
Wendy (CokeCachers with Mike, 1300 caches found so far)