on the bow of my boat i put a 5200 gps and a x510 sonar. up in the fishing station at the front of the boat i prefer two separate units side by side instead of splitting the screen on one larger unit. it’s cost effective, and they are great units, well within the price range you noted. obviously lots of people here using and recommending the 500-line from Lowrance – for good reason.
on my console to save space i go with one bigger unit running a split screen for trolling, just the map with depth overlays when running on plane, or just the sonar when i want to see something more specific.
for this i’m rigged with a Humminbird 917, a unit which i absolutely love. big 7″ screen with great clarity/detail, and the map readability is very very good. one limitiation with the Humminbirds is that you can only run the Navionics chips and not the Lakemaster.
the 900-series includes a couple of versions: 917 (mine) which offers dual-freq sonar, the 957 with 4-beam sonar, the 967 with “3D” sonar, and the 997 with side-imaging sonar. all in the neighborhood of your price range.