Mike,
You wont go wrong with any unit from the main manufacturers - Garmin, Navman, Lowrance (Eagle) Raymarine, Furnuo etc..
Garmin, Navman and Lowrance probably have the biggest leisure following in our size and boat useage.
Furuno, Simrad and Raymarine are all starting to go towards commercial use and whilst are still leisure units, they arent as intuative as the ones above.
Size wise - I know what you mean. Personally I managed a 10.5" plotter for your budget - just, but had to add the charts - another