You'll cast a much wider net if you put it on Craig's List, and if that doesn't work put it on eBay (as a fixed-price or best offer) and "good till cancelled". You might also try the Ericson owners group, wherever that is. It might hang around for a while but when you find the right buyer it'll sell.

You can do really well selling boat parts on eBay. When I upgraded my radar to broadband I parted out the components of my old Raymarine system, and got back almost as much as the new Lowrance system. People will pay for working exact replacement because it's cheaper for the part they need than a total system replacement, and less headache than total new installation of something new and different.