Not to be a wet blanket, but I started out with my usual degree of enthusiasm, found lots of caches around LA, but by no means all. I'm sort of cool on geocaching now. If I'm going somewhere with young relatives, or interested friends, I'll load up the recent cache list on my Garmin Venture HCx. One thing I find futzy with this lower priced model is the 25 megs of storage space (or whatever it is) does require me to basically unload all the LA data that's useful when I'm in town so that I can upload new data for say Phoenix or S. Francisco where I have young relatives. If I ever get another GPS, it's gonna have all the detailed data for the U.S. built-in, or at least easily loadable on a SD card, with plenty of room to load caches for any new areas I might be interested in. The Venture HCx is a very excellent unit for the price, as I've said, just short on storage which I accepted as a cost saving measure when I bought it. Knowing what I do now, I would have saved up a little more money for better storage.

My Magellan is so old it has no map and no PC interface. I fat finger cache positions in using the rocker switch to select the numbers. The need for geocaching is to show your position and the cache position in relation, so something as simple as a Garmin Geko would work. A track back type of feature (shows your breadcrumbs) is nice if you go off trail to find the cache.

GPS is just like the rest of the gear. The basics are often sufficient unto the task, but bells and whistles are oh so pretty...

Tangent: I recently went to look at a new vehicle. The salesman spent more time going through the interactive entertainment features than anything else. I had to ask him to pop the hood so I could see something truly useful.

I just noticed a local sale -- Magellan Triton 200 and 300 for half price ($80 and $90 CAD, respectively).

Anybody have strong opinions on these? It's a great price, but I don't want to throw away money on a clunker.

EDIT: I just looked up the Web reviews for these units. The consensus seems to be "dude, run away!" So maybe this is another example of how the Web saves me money. Guess I'd better hunt for a basic Garmin.

Any thoughts on buying a used GPS? Wise or foolish? How would I test it?

I started out Geocaching in 2005.
I used a Garmin Legend till late last year. I kept talking myself out of upgrading since the Legend still worked perfectly fine. Yes, a color screen would be nice and a more sensitive receiver and finally broke down after many months of debating.
I was looking into the Colorado and Oregon and found most liked the Oregon better the the Colorado for Geocaching. A nice feature with both units is that you can download the info into them about the caches you are searching for, "Paperless". Such as cache size, Description, Last logs by other finders, etc.
The Oregon cost more then I wanted to pay, plus the "Paperless" feature did not mean that much to me since I use a PPC for the cache info.
I ended up buying a Garmin GPSMAP 60CSx. I love this GPS.
Bought it new off ebay, shipped to my house for $270.00 which was a great deal when I purchased it. I just did a search and see I can find a new unit shipped for $281.00.
I would also recommend the TOPO maps to load into the GPS.

As for a used one.. not sure about that one. Maybe if it was a friends who was upgrading.

I appreciate the honest comments. And yes, there's no point in buying inadequate gear; it just costs twice as much in the long run. But this is starting to look like a black hole for hard-earned cash. So I'm open to wise suggestions ... how do I get into this without having the wallet ripped off my butt?

If your thinking of trying this out and seeing if you like it, get something like the Garmin Legend. The original (non-color screen). I think I've seen them at Dick's or other sporting good stores for around $100.00.
Or I looked around and found a brand new, not a referb, Garmin Legend CX, color screen for $129.99. Refebs at around $105.00.
It's a good trusty GPS.
The original Legend I used almost 4 years and over 700 Geocaching finds.
Both come with a very basic, not much detailed base map, as do most models. You can get TOPO maps which I use, and love, but the thing with the Legends is that they have a fixed amount of memory for the maps which is small. So if your going out of the area of your "standard" maps you would have to upload the new area maps.
Maybe find out if there are any Geocaching groups in your area. There's a group that meets every 4th Thursday of the month around me. Maybe you could find someone who has an old one around they could let you use for a bit a to make sure it works and then purchase it???

Your only investment would be in gas & a GPS. I know you've been pointed to geocaching.com; they have device reviews there now (unless its for premium members only, but I dont think it is). That may help you decide which GPS. You CAN do it with even the most basic GPS and a little mapwork; I did about 45 finda with nothing more than a garmin 201, which is their wristop gps. that was simply a breadcrumb trail that I could follow, no maps, nothing. Just wanted to throw that out there for ya.

Where can you download maps (free) that are good enough to use?

The US Geological Survey has a map server called the National Atlas.
Canada and Mexico have similar services.
You can download from Google Earth too.