I am looking to buy a blackberry online and want to know if it has to be "unlocked" in order to use it with Sprint? What should I look for when purchasing one (and not wanting data)? I need to somehow transfer my number to it... Can anyone give me as much help as possible please?

Be careful - Sprint will normally only allow Sprint branded devices on their network.

No such thing as "unlocking" a CDMA device. Be wary of the seller.