I recently bought the Explorist 600 for $289 from Harmony computers, based on a tip in this forum about the price. I bought Mapsend Direct and downloaded the extended manual off the internet(a must). I also bought a SD memory card on sale at Best BUY.
I spent a couple hours learning the unit and Mapsend and very quickly created a base map of a large area around Bristol TN and went to the Nascar race this past weekend. This unit, my first GPS, worked flawlessly. I "marked" the hotel and also created waypoints/POI's for race shops and the 600 was just invaluable! I highly recommend it based on the ability to connect to a computer, add a memory card, and the rechargable L-IOn batteries.