Finding a best deal formula for trade and buying

To start with, NADA is an approximation of value. In automobiles it is based on reported sales and in RV land it is a percentage of the original MSRP. If you had two 2006 Honda Accords with 50,000 miles and one was $12,000 and one was $8,000, which one is the better deal? You cannot know, since there is much more to the valuation than what can be expressed by age, make and mileage. Condition, options, location, color and a host of other issues all come into play.