how much was dual spec in wotlk

In World of Warcraft: Wrath of the Lich King, the Dual Spec feature allows players to learn and subsequently change specializations on the fly, without having to go to a class trainer. The cost for learning a second specialization is a mere 10 silver, and does not require any gems, scrolls, or reagents. The change can be made at will, outside of combat. In order to accommodate the new system, Blizzard increased the number of available talent points from 71 to 81. The first dual specialization was available with the release of the expansion, on November 13, 2008.