Straight from the Blizzard Site comes this:(Yes, I copied and Pasted, Don’t Sue Me Blizzard, You’ll get no money, I’m broke!)
Character Faction Change
Welcome to the Faction Change page! This service lets you change a character’s faction from Alliance to Horde or from Horde to Alliance. A mandatory opposite-faction race change is part of the faction change process, and the full range of customization options offered by the Character Re-Customization service is included as well. Each faction change costs $30.00 USD.
Things to know before you start:
- The faction change process is not immediate, and a character will not be available for play while a faction change is pending. Under normal conditions the process should take under an hour, but please allow up to several days for a faction change to complete.
- During this process, you will select a new character race from the opposite-faction races that have the character’s class available. You cannot change a character’s class.
- To see how character-specific information such as achievements, reputations, and items are affected by a faction change, refer to the Translation Table.
- A realm transfer is not included in a faction change. However, the restriction on having members of both factions on a PvP realm has been lifted, so you can have characters of both factions on a single PvP realm.
- A character can change factions once every 60 days.
- Not every character will be eligible to undergo a faction change. If applicable, the reason a character is not eligible will be brought to your attention before payment is rendered. For example, faction changes may not be possible on certain realms or only one “direction” of faction changes may be allowed on a given realm.
- Please refer to the Character Faction Change FAQ for answers to common questions about this service.