For under $100 there is no better GPU than this http://www.newegg.com/Product/Product.aspx?Item=N82E16814150688&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=
If you spend extra the next best GPU is the 7850 but that costs $110.