Just for refference, My truck in March '04 cost $15,500 It's a 2000, 2wd, LS 4.8L, EXSB, and had 45,000miles at purchase from a dealer with warranty.
If you want to know what is too high in your area, look up the truck on
www.nadaguides.com ,
www.kbb.com , and/or
www.edmunds.com . Look up both trade in value and and what you would expect to pay from a dealer. This will give you an idea of what numbers to play with!