They are selling OB Starter Kits in the online store, which will give you some in-game items as well as access to server/character pre-selection, but I don't think it is required to play. Just add Aion to your PlayNC account and you should be able to play on 7/7.
Have a look at
this page if you need instructions on how to sign up. If you played CB you still need to perform the step to add Aion to your account, and you will be given a "ticket" for pre-selection.