Humminbird just recently dropped the price on their 360 Imaging transducers significantly. These are some of the greatest tools out there for the serious angler. I believe Humminbird's 360 technology to be the biggest advantage an angler can have over the competition because it shows you everything about the spot you are fishing.
You can add the 360 transducer to just about any boat that is running a Humminbird unit with an Ethernet port. They are available in a transom mount version http://radioworld.ca/as-360-ssi-p-6340.html
or
a bow mount version that will work with cable steer trolling motors like the Fortrex http://radioworld.ca/as-360-tm-p-12707.html
Here is a video I took while using the 360 last year on Lake Erie