I was looking to pick this up and this is the cheapest price I found $44.99 at Buy.com + Shipping. I ended up paying just under $50 for the whole thing which is a good deal.
http://www.buy.com/prod/xbox-360-halo-reach-wireless-controller/q/loc/108/216991522.html
http://www.buy.com/prod/xbox-360-halo-reach-wireless-controller/q/loc/108/216991522.html