The best cases for 100$ is the Corsair 400R- http://www.newegg.com/Product/Product.aspx?Item=N82E16811139008
and the BitFenix Raider- http://www.newegg.com/Product/Product.aspx?Item=N82E16811345009
. They both have many removable dust filters that make it easy to keep your components dust free and heat sinks free of dust aiding cooling. They also both have 3 120mm fans which moves plenty of air to keep your future SLI setup cool. In addition, These cases have cable management holes with rubber grommets to make it easy to hide any unused cables that could have otherwise impeded airflow.