pre-order on Amazon. The price is $34.99 but hopefully will drop once get close to the September 13, 2016 release date. There is no mention of "exclusive" so its possible this version will be available elsewhere.
On a somewhat related note, Transformers: Prime the Complete Series Boxset (3 seasons) is also available for pre-order. Release date is August 12 with current price of $144.99 which mostly definitely has to go down by the release date.