Update: Apparently, you can just buy it.
Spend $11.99 or more on a LEGO Star Wars set, and get a free Chrome Stormtrooper polybag figure. Basically, buy a battlepack and it’s yours. This deal is good for US Toys’R’Us retail locations as well as online. I couldn’t find an end date for this promotion, so I assume the offer good while supplies last. Don’t hesitate, get thee to a TRU now!
Thanks to doodlebird for the heads up.