I have been getting a lot of these questions lately so I will give you as much info as I can.
The price depends on
where you live, the trim level of your vehicle and its condition as
well. Because I don't know all of this, I can only give you an idea
based on Kelley Blue Book's results.
The suggested retail value of a 2000 Cadillac DeVille Sedan 4 Door with 13k miles in excellent condition is worth: $11,210
that trade in values are usually lower and private party values are
usually higher. Try playing with the tool on www.kbb.com and see if you
can get it to be more accurate for you.