Lots of GPS/Sounder units out there for a reasonable price new from Garmin
now that Lowrance and Humminbird both have 2 generations of HD structure
scans.

I have a couple of the older simple LCD graph Garmin combo units and they
work just fine. I've had them for several years, and the only issues have
been damaging transducers skipping sandbars and fishing in ultra shallow
water. Not something you are likely to be doing with a sail boat.