I suggest Furuno LS-4100 or Garmin 160.
Furuno LS-4100 is less than $200 and is available with shoot-through-the-hull transducer. Garmin 160 is also in that price range, but not sure about the transducer
I've seen some negative post about the Furuno LS-4100 and LS-6100. It boils down to 2 complaints: clutter at the top of the screen and no depth reading in water under 3 feet deep.
I own the LS-4100 and my unit has both of these "problems", but they don't bother me. It seems that most units have clutter at the top of the screen. Also, I find that many units stop marking bottom when the water gets quite shallow. It might be 2 feet instead of 3 ft on some other unit. Either way, we're talking about pretty shallow water and the operator has hopefully slowed down and is being cautious by the time the depthfinder stop marking bottom.
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Fishin-Fanatic
Get In! Sit Down! Shut Up! Hold On!