How much of a 'friend' is the friend? I would start the ball rolling by asking your friend what their expectations are for financial return. If he/she 'just wants it got rid of' then you've got lots of room to move on price. Do the research that Bob suggests then give the machine a thorough going over and subtract from that magic figure the cost of the tyres, battery, tune-up parts, fluids, chain/sprockets(?), carb clean, tank fluch and clean, etc,etc, that it will inevitably need.
Personally I would never cheat a good friend.
This sounds really interesting, so please keep us in the loop. Post pics. And don't be disappointed if by the light of day it turns out to be a K8. (Ooops, sorry Eldar!)