For color, sonar, & GPS on a budget look at the Lowrance M68c. I have one and don't mind it too much. Worth the $400 at least compared to the more expensive units.
Only real complaint I have about it is the mounting bracket. I've had mine for about 18 months and think I've broke about six of them. Only $11 to replace but really makes for a tough day on the water when it does break.
You can also use it for ice fishing and it works ok. It's not a vexilar, but if you were looking to get double duty out of one unit, it's a plus.