redbug said:
in that price range any unit you get will be junk.
you will not be happy with any of those units and will be looking to upgrade again
save your money until you can afford a quality unit.
Remember the more vertical pixels you have the more detail you will see.
I would be looking for a minimum of 320x320 pixels
Junk is a little bit harsh and I apologize. I should have said that in that price range the units available will not do much more than the unit you have now.
the eagle Fishmark 320 is a very good unit that gives you :
Depth capability to 800 ft* (244 m) with 1500 watts of peak-to-peak power
High-performance, low-profile 200 kHz Skimmer ® transducer delivers a wider, more effective fish detection area of up to 60ø with high sensitivity settings - Operates at boat speeds up to 70 mph (61 kts)
Trolling speed and distance log readings available with purchase of an optional sensor
FishReveal™ feature exposes fish targets hidden in surface clutter, weed beds, thermoclines, and other types of underwater cover
HyperScroll™ feature locates and displays targets at higher boat speeds
Advanced Signal Processing (ASP™) automatically adjusts your settings for the best sonar picture
Patented GRAYLINE™ separates fish from nearby structure and bottom
Advanced Fish I.D.™ shows underwater targets in different sizes of fish symbols
FishTrack™ displays target depth readings above fish symbols
Surface water temperature readings come from a built-in temp sensor in the transducer
Unique display feature lets you combine a panel of sonar data readings with your sonar graph in one easy-to-read display
Zoom with zoom bottom tracking and easy zoom-in/out control
Selective on/off sonar alarms: Shallow, Deep, Fish and Zone
Performance:
High-speed screen updates during depth range changes for uninterrupted viewing
Internal back-up memory for key sonar settings
Completely sealed and waterproof, even for use in harsh saltwater environments
Full one-year warranty
and can be found for around $160.