[tsubaki]

Depends on what you want, color screen, depth, temp, gps, map, weather, single, dual or side sonar.
I'm partial to Humminbird, price, dependability and most major portions are available at the 24hr Walmart. If its stolen or damaged the night before a fishing trip just pickup another and plug in.
The 363, 580 and 161 have gps, depth, temp and a couple other things.
The 161 is $288 (plus tax) at Walmart and $265 (plus shipping) on e-bay.
Small screen is the norm with these Humminbirds, this is what other people hate about them.
Be sure and check the max depth on each unit, some only go to 600' (I'm normally well under 100' fishing).