I fish here in SE Louisiana.  The waters I fish are almost always under 10 feet deep.  Of course I need the sonar for locating  fish but, I also need a REALLY GOOD picture of bottom structure because I recover sunken logs for sales to furniture makers. 

Many of these logs are mostly submerged into the soft muddy bottoms.  If I understand correctly, some reviewers say that soft bottoms interfere with the image.  I mentioned possibly using scuba gear to locate logs.  However, one of the log buyers (not a log recoverer) told me that a $2000.00 sonar is what I really need.  Is this the price range I'd have to pay to get the best picture of the bottom under and to the sides of my boat?  He said that some fishermen have told him that they can actually see their fishing line on the image.  

We catch big redfish, sheepshead and catfish  in the same water as we catch our bass in.  I keep the redfish, catfish and sheepshead and release the bass.  It will amaze me to get a clear image of the fish I'm targeting in these bayous and canals. 

Having a GPS unit will allow me to mark locations of the logs and mark the spots where I have the most success fishing.

 

Since I only have experience with the newer Humminbird units, look at the Helix line with Sidescan Imaging (SI).  They give you the traditional 2D sonar as well as great SI imaging.  Well under $2000...with built-in GPS. 

 

This is with Lowrance DownImaging

A couple more.