How much does an xbox 360 wireless adapter cost?

I believe it's $99. It's the same price as this:

http://images.bestbuy.com/BestBuy_US/en_US/images/abn/2009/com/pcon/netgear_pwrline/netgear_powerline.swf

http://www.bestbuy.com/site/NETGEAR+-+Powerline+Ethernet+Adapter+Kit/8919708.p?id=1214004487426&skuId=8919708&st=powerline

which is much simpler to connect than the Xbox adapter. You'll get better performance too.