Where can you buy Lord of the Rings battle for middle earth 2 rise of the witch king

You can buy a copy at amazon.     http://www.amazon.com/Lord-Rings-Battle-Middle-Earth-Pc/dp/B000HAUO4A/ref=sr_1_1?ie=UTF8&qid=1364233417&sr=8-1&keywords=lord+of+the+rings+battle+for+middle+earth+2+wrath+of+the+witch+king