Koetsu Gold

I have an early 90s Koetsu Gold (at that point their top of the line, stone bodied (not wood) with original box) sadly little used, apart from very rare occasions, in recent years since the arrival of children. It still works magnificently but assume a re-tip is in order. My question is what is it worth - I know it's what someone is willing to pay, but that seems to vary according to whom I speak. As the new equivalent model seems to be around 7.5k and this was made by the original master I am interested in your feedback.

regards,
Nigel.