Party A is selling a 10K car.80% chance it will not break down during the first year.

Party B 80% chance it will break down during the first year.Negotiate

I dont know where to start. I thought about going through a typical negotiation where they both settle around 5K In other words, PartyA moves to 5K and Party B comes up to 5K. This is not acceptable to Party A. So he does a contingency agreement, Stating that if Party B comes up to 6500k, he will offer a contingency agreement that if the car breaks down in the first year, he will pay up to 1,000 in repairs. He is taking a risk but he is 80% confident the car won't break down. He gets 6,500 and a reasonable expectation that he will keep every penny. Party B has some confidence in knowing that if the car breaks down she has 1000 dollars to spend on repairs. Unfortunately,

Party A has had the car for sale for several weeks and has had some "low ball" offers in the 4,000 range. Does this seem reasonable? Am I missing something? appreciate all help