The World of Warcraft character upgrade interface was spotted yesterday after US servers came back online following maintenance, revealing a level 90 boost to cost $60.
MMO Champion notes that the $60 price tag may be a place holder, and is subject to change once the facility launches on live servers.
The ability to pay to boost characters to level 90 comes in addition to a free upgrade for purchasing Warlords of Draenor - those who have pre-purchased got the boost early.
Warlords of Draenor lifts the level cap to 100.
At $60 this is costly enough to ensure those who have put in the grind don't feel short-changed by Blizzard. Dishing out level 90 boosts for $10 may have been poorly received.
Source: MMO Champion