A suggestion on the lines of the original post;
I use a Garmin 300C Fish finder that I picked up for my boat last year. I was able to get this great color unit new for $225 including shipping. It has every feature that I could want including; zoom, Split screen, battery voltage, temp, Dual beam (15 or 45 degree), gain that has 100 points, great separation, flasher screen if you want old school and many more features. I put the boat transducer on a old tip up frame and the unit is in a small lunch box with the battery. I see guy getting $400 units that have the same features... Garmin is in the USA and has always been great with customer service for me.
There is more than one way to fillet a fish!!!