McDonalds actually came out about a month or two ago and stated that they will be upping the price of their double cheeseburger to $1.29 and will be replacing it on the dollar menu with some double hamburger-esque alternative due to the rising cost of beef and dairy to them.
That being said, they have to put wording like "Prices may vary" mostly due to certain locations simply not following general corporate pricing structure for their own reasons. I'm sure many of you have stopped at rest areas along interstates and whatnot. While I have never seen a Pizza Hut in one of those up here in MA, every chain that I have seen placed in them has had a menu with often times greatly increased prices. Going back to the McDonalds example, you'd be hard-pressed to find even a $1.29 double cheeseburger along I-90 -- instead you can expect to pay $2 and change. Deal menus go right out the window along with 'normal' pricing. The corporate lawyers are smart enough to not let their company get dragged into any kind of 'false advertising' claims over silly things like that
