It all depends on condition, miles and options. In good shape maybe $3 to 4,000.
If you are using it as a trade in, it may appear you are getting a good price, but the dealership has a lot of leeway in the selling price of the new vehicle. They won't keep a vehicle on their used car lot anyway. Do a little research on the net and see what others are asking for a similar vehicle. I recommend you do not do a trade-in.
Search Ford F-150 Questions
Ford F-150 Experts
Related Models For Sale
Used Cars for Sale