Although you can obtain a character boost all the way to 90 by pre-ordering Warlords of Draenor, you'll also be able to purchase them freely from the in game store. For $60 and under the "services" category, it's as easy as hitting the token in the character select window. Surprisingly, Blizzard have actually been pretty generous with what they offer for your money. Not only do you get a level boost, but you'll also get level 90 gear, a full set of bags, be teleported to the new leveling zones and have your crafting leveled if you're already level 60.
Personally I think it's pretty awesome and for $60, a bit of a bargain. If you only play World of Warcraft, its hardly any different than going out to purchase a new game. I know for a fact I'd buy one if I were still playing. The biggest concern I have however is the fact that will players level any longer?