I suspect that the Sierra Denali would be more expensive than the F150 he owns... but I could be wrong. It really depends on what trim level the F150 is. I have seen some (as well as Chevy and Dodge) that are customized and just as nice (or more so) than a Denali...
What if he put a topper on his truck and got rid of the f-150 badging and said it was an expedition? =-p