Many thanks Tom! This really helps me get going. I have been hunting this morning on the net, and I see yet another Garmin unit that looks just like the ones you noted.
Here’s one called the Garmin GPSmap 298 Sounder / Chartplotter with internal antenna, all for $384. Since I don’t need or want the sounder, I would be paying for something extra I'd never use. After looking at the Garmin lineup, my hunch is all the units that LOOK like this one, probably have the same GPS chart plotting technology, and they seem to be repackaging them as fast as they can to keep the price points up.
http://www.nextag.com/Garmin-GPSMAP-298-Sounder-500677675/prices-html
The more I look, the more I like that 172C you noted. It looks like the basic GPS unit without all the bells and whistles, and a much lower cost. Prices vary wildly too!
Great reference for the NexTag shopping. I bookmarked that one.
Dave