The new
Garmin 440 has a 4 inch color screen and comes with all the US coastal maps. You should be able to find it for $500. A lower cost choice is a
handheld unit. A Lowrance iFinder H2O with a chart card can be had for $200 or so. That said, I assume you will also have paper
charts of the area you will cruise. I consider the electronic
charts a convenience, but not a substitute for the paper ones.