You pay a lot for the case. Just another idea - A lot of guys get double duty out of the finder they use on their boat for fly-ins or ice fishing.

You make a box & buy a spare power cord, bracket, and puck transducer, suction cups are available as an access or mount the ducer on a board and c-clamp to transom (there are commercial versions too).

Battery - Cabelas sells 7 amp hr sealed 12 volts for ice fishing and cameras. Proper care and they last many yrs.

Good Luck,
SS