Bought one for my pontoon. Would have put this in the hot deals section, but was afraid no one would see it in time. Sale lasts for a little over 3 hours, and once they're gone they're gone!
http://www.amazon.com/Humminbird-Fishin-4-Inch-Waterproof-Fishfinder/dp/B0012BNKMG
http://www.amazon.com/Humminbird-Fishin-4-Inch-Waterproof-Fishfinder/dp/B0012BNKMG