This might get moved to the 'What is it Worth' section but I'll answer in the meantime. Quite a few questions still need to be answered. Any maintenance records? All the fluids should have been changed with the age and miles of the car. How many owners? How is the clutch, tranny, brakes, etc... and the most important thing, how does it run? If you can answer positively to most of these questions, then the car is priced accurately, especially with the 'best offer' attached. An excellent buying price for you would be around $9,000 if everything checks out. If the car is truly in GOOD Condtion, and needs very little, I would move closer to his $10,000 asking price. I'm sure he would take $9,500 or $9,600 or otherwise he would have said $10,000 firm. A non-modded WS6 with 6 speed is a nice find if not abused. Also make sure it is a real WS6. Good luck!