Apparently, one custom private server is asking for real money in order to play during the BETA phase. It looks like they are also charging money for different in-game stuff. At the end of the BETA testing, they will delete your character, together with everything you purchased. You won't get a refund.
Private servers are free! Don't pay for something that isn't even out yet. The guys behind this project WoW Awakening might end up just closing the server and you won't be able to refund your money. Stay safe.