Personally I'm looking at the Humminbird 777c2. It has the same processor and features of the flagship 787c2, but no GPS. However, you can add the GPS unit to it should you want to at a later date.
Bass Pro and the like have 'em for 499.99 and up, but I've found them consistently online for around 425.00 w/ dual beam transducer NEW, or around 390.00 w/o transducer should you want to go the quadrabeam route. Just by going to places and messing around with the demo units it just seems to make sense to me to go ahead and go color. The high resolution 640 x 480 of the 777c2 makes it best all around bang for the buck.