In store only.
Item number 554488. Unfortunately same item number for all three versions,
so no way to know exactly what is in stock. Wii version seems plentiful, saw
a few for PS3 and none for the Kinect. YMMV for the versions at your local
Costco.
Amazon link: http://www.amazon.com/EA-Sports-Active-2-Nintendo-Wii/dp/B003O6
for reference and reviews.