Promo just started, and will end 26th Feb or while stocks lasts. It's good that they're not limiting this to just the Lego Batman Movie line.
https://shop.lego.com/en-AU/batman-m...gift-promotion

T's & C's.
LEGO® Disco Batman™ Tears of Batman™ set (30607) is valid for orders online at shop.LEGO.com, in LEGO Stores and LEGO Catalogue telephone orders from February 6th to 26th 2017, or while stocks last. Qualifying purchase must be equal to or greater than $100 in LEGO merchandise only. One LEGO Disco Batman™ Tears of Batman™ set (30607) per household.