Whenever you see a buffet price at WDW that doesn't end in ".99", you can pretty safely assume that it's a tax-included price. (Or, it could be just plain *wrong*, I suppose.)
Then there are just two issues to figure out - first, does it include holiday pricing? And second, is it out of date?
For the first, it looks like most WDW dinner buffets are in the neighborhood of $32.99-$35.99 these days without holiday pricing - Crystal Palace and 1900 at the higher end.
Hard to say with the second - they typically creep up by two bucks or so. While overall price increases are normally not announced in advance, calling WDW Dining can get you the price on a given date *as of right now*.