I had similar Cannondale, an SR800 that I threw on ebay with a 'Buy Now' of $450 and a best offer of $400 or higher. Its sold in less than 4 hours. My bike had DT shifters versus the STI's this bike has.
If I had to guess, I'd say the bike in question will sell for $450-500. I'm not sure if the headshock helps or hurts the value.
My infamous SR800:
