Buying a porsche 951 need some advice

Hey, I'm thinking about purchasing a 1986 porsche 944 turbo.... unfortunately my 1983 porsche 944 has seen better days.. R.I.P.... The 951 has 71k miles and is in great condition. The belts need to be changed soon though. The car runs well, and barely needs any other aid besides the timing belts. The seller is asking for 15,000 obo... roundabout how much should i offer him. thanks for your help

I'd start negotiating at around 12. gives you plenty of room to negotiate. what's the blue book on this.