I don't know how long this has been available on bestbuy's website, but they have the special edition of 300 with the helmet and art cards listed again at $34.99. This set sold out within a day when the movie was released.
Link:
http://www.bestbuy.com/olspage.jsp?id=1665792&skuId=8411408&type=product
Link:
http://www.bestbuy.com/olspage.jsp?id=1665792&skuId=8411408&type=product