I went into bass pro looking at a 2d sonar/GPS last week. I was in the $400 range when I was looking. Ended up spending the $50 more to get the GPS with it all. About double what you are looking at, but can do it all, and should make you happier in the long run. Another option would be to look for a used unit somebody is selling. Before I had this unit I stored all my fishing spots in the handheld GPS I used for duck hunting.

Humminbird® 587ci HD DI GPS/Fishfinder Combo | Bass Pro Shops