Dual talent specialization is made available to players at level 40. I do not recommend purchasing the talent at this time unless you have a main toon with a surplus of to fund this endeavor. However at level 80, dual talent specialization is a no-brainer for most classes. At the cost of 1,000 gold any player should be able to afford this and the benefits are great. As of note, there is no type of faction discount that can be applied for the talent. You can purchase the talent from your class trainer.