I have the Furuno LS6100 monochrome hooked up to a thru-hull 'ducer. It works really well and is easily viewed in sunlight. I get bottom readings all the way to WOT (34-35 knots), but shallow water (<6 feet) readings are not great.
I bought it from Dave's Marine Electronics -
www.brokenlegdave.com - for around $260 if I remember correctly. That was without a transducer, plus being part of a package deal (FF, chartplotter, VHF).