I would go to places like edmunds.com or kbb.com or nada.com to get a better idea. I have found edmunds.com to be the most up to date on prices though, I just checked with the info you gave and I got a trade in value of $25,000. You might try it yourself because your zip code might change a few prices and options...
good luck
, and if you get an ecoboost, let me know how it drives!