Yes, buy from Samsung Service Center, with warranty. I bought battery for my old Samsung GT-I9001 mobile from a local Samsung store. Locate a local store near you using the Samsung site.
Where did you check.. online or local stores of Samsung? Mine is a pretty old phone, and its battery was available. No harm in trying the local stores.
Local stores may have duplicate batteries , they are bad . Go to service centre or buy from estore if available . You get a bill with the batteries serial number on it and a six month official warranty . Have done this for my galaxy note and galaxy pop cdma before too .