If your fishing inshore as it appears you are, you can get a good unit for well under your budget.
I had the luxery of free electronics from Raymarine when i lived and was guiding in the keys.
Now i buy my own and frankly what i had was way overkill for what i actually needed. Florida sportsman
sells chips showing all the wrecks and known hotspots for the entire state in a regional format. I have most
of the state entered into my current small Hummingbird unit. So i really only need the unit to steer from point a to point b
and the depthfinder keeps me out of trouble while running. I had a large list of spots in the keys but many of them are
also on the chips i now have. My unit has down imaging but not side scanning. I frankly think most of those type features
are pretty much worthless unless you enjoy playing with the units more than fishing. Some days i never even turned my machines
on when i was in the keys. If things were slow i used the fishfinder, but otherwise i just used my waypoints and kept moving till we had fish.
Tide and current are also very important and that requires knowledge of the area more so than the electronics.