Thanks for all the information and advice guys, but it turned out the seller's sentimental value far exceeds its resale value. After telling him how it would be going to a good home etc, I offered him 5000 cash. His reply was "i want at least 10,000"

Personally, i question wether or not he will actually ever part with the car. If i had said "i'll give you 10,000" - i suspect he would ask 20,000

Anyway, we parted company with a hand shake and i left him my number should he change his mind down the road.

All in all, with the info / advice and my own instincts - i feel that 5000 was a fair & reasonable offer.