Had this in my boat for about 3 years. great condition. comes with 50/200kHz transducer w/ temp and paddle wheel speed. These went for around $1100 new. I found a couple used ones around $600. I'm asking $350. you can find the owner's manual here:
Humminbird product manuals 
It has always been removed from the boat and stored indoors. The transducer is still installed on the boat at least until Sunday this week.
willy
Posted by: landcruiserwilly
Re: Humminbird 931c DF Fish finder - 05/07/14 06:00 PM
BTT for price drop. $250 for a 7" color fishfinder.....
willy
Posted by: landcruiserwilly
Re: Humminbird 931c DF Fish finder - 05/15/14 01:17 AM
someone needs one of these...
some info from the interwebz:
•Brilliant, 7" sunlight viewable color display with 480V x 854H resolution
•Precision 200kHz or dual frequency 50/200kHz tranducer options
•750 Watts RMS, 6000 Watts PtP (200kHz) power output, 2 1/2 target separation, 1000 ft depth or 1000 Watts RMS, 8000 Watts PtP (50KHz) power output, 2 1/2 target separation, 2500 ft depth**
•Memory card expansion slot to save Screen Snap Shots or optional cartography
•Dual microprocessors and dual channel sonar transmitter/receiver deliver fast, smooth operation
•GPS Ready - Full screen trackplotter, 3D track and split screen sonar/track with adjustable split
•Programmable View Presets Access Important Screens with one touch
•Plug & Play compatibility with the GPS Receiver, WeatherSense Barometric Pressure, Wireless Sonar Link Advanced Accessories
•In-dash or Gimbal mount
willy