I think that's an Exxon Graftek, the first-ever carbon fiber bike, which debuted in 1975. I would not personally be comfortable using one as a regular rider, as they had problems with the bonding technology used and may not be safe. They were eventually discontinued as a result. So the value is primarily historical, unless someone wants it mainly for the parts. Might be worth several hundred dollars if sound. (BTW, that stem is perched high enough to cause real problems if its ridden that way). More on the Exxon Gratek here:
Holy giant photo, Batman!
Laterally stiff yet vertically compliant.
Viscount Aerospace Pro Trek 770 Cannondale Synapse
yah i was motivated to put up that HUGE pic to help ppl look and identify it!
brakeset: $75 (with good hoods)
Framset w/ BB and headset...... Not sure.