Sold out? Not really...
R9 270
http://us.ncix.com/products/?usaffiliateid=1000031504&sku=92096&vpn=AXR9%20270%202GBD5-DH%2FOC&manufacture=PowerColor&promoid=1223
http://www.newegg.com/Product/Product.aspx?Item=N82E16814121823&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=
http://www.newegg.com/Product/Product.aspx?Item=N82E16814202062&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=
R9 270X
http://www.newegg.com/Product/Product.aspx?Item=N82E16814131532&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=
http://www.superbiiz.com/detail.php?name=AT-R9-27X2&c=CJ
If you already bought the GTX 660, just install the latest drivers from Nvidia.