Looking at a 18' Whaler Outrage, with a Yamaha 150, on a EZ Load trailer (all 1988). The average price at NADA for the 1989 is $6340.00 for the boat and motor I figure a grand for the trailer and that makes it $7340.00. I figure it should sell for about $9000.00. The asking price is $11750.00. The package is in excellent condition. My question is how do the NADA prices figure into what I should pay for a boat?