Update: Noticed the tax increased the amount from $14.99 to $16.32 total. The WoW Token won’t be enough to cover that. I had to add $1.00 via credit card to complete the amount.
Diablo III: Rise of the Necromancer is on sale after June 27th for $14.99, but you can get it for Free with a WoW Token. Free in the sense that there is no actually cash or credit card involved, but it costs World of Warcraft in-game gold instead.
This is how to buy Diablo III: Rise of the Necromancer with a WoW Token.
1. Go to Orgrimmar or Stormwind.
2. Open the Auction House window.
3. Click the WoW Token tab.
4. Purchase the WoW Token for 128,901 gold. (This amount might vary from server to server and location)
5. Go to your in-game Mailbox.
6. Click the WoW Token in your bag/inventory. A window opens onscreen asking you to choose Game Time or Blizzard Balance. In this case, choose Blizzard Balance.
7. What this does is give you credit for $15 in Blizzard Balance. Diablo III: Rise of the Necromancer costs $14.99, which make it Free at the cost of World of Warcraft gold.
8. If you go to the Battle.net Account Management page (USA | Europe) you can now see $15.49 in your Battle.net Balance.
Update: The tax raises the cost to $16.32. You might still have to use a credit card to add a minimum of $1.00 and it might take up to three days for the Blizzard Balance to update the extra amount. As discovered today, it turned into a hassle.
9. On June 27, go to Diablo3.com and purchase Diablo III: Rise of the Necromancer using your Battle.net Balance.