so, i'm beginning researching chartplotters for my boat. this would be used primarily in the salt, typically puget sound. i would like to get one in the 4-5" range, as both my budget and space limit the size of the unit. i'm not looking for a combo sounder/GPS as i already have a nice wide screen humminbird ff. bottom contours (quality of map) , ease of use, useful features will be considered. networking, interfacing with other devices, splitting the screen are things i don't think i'll really consider. if I can spend less than $500 it would be a bonus.

question:
are the built-in coastal maps good enough, or do i need to budget for a navionics/Cmap/etc chip as well?

thanks,
willy