theres a few out there to chose from these days thats for sure
best sonar quality per dollar is the garmin striker range , the 7SV in perticular , with its gt52 transducer up to that 50/60mt mark is exceptional. ....and idiot proof.
where the striker lacks is in MAPPING. whilst it does have gps functionality. "where you have been, waypoints, speed etc" it wont show mapping. this is fine if your fishing inland and those inland inpoundments dont have mapping anyway. otherwise id be looking at other models.
the 7sv is $750
if you go down the 5" model you drop "sidevu and high frequency chirp" for the 5dv model. but you also save a pretty penny
striker 7 sv
striker 5dv
both systems will leave you some coin in your pocket.
Moose