Due to its cheap price, natural gas has become extremely popular. As a result, Clean Energy Fuels ( NAS: CLNE ) is building a nationwide network with an anticipated 70 filling stations in 33 U.S. states by the end of 2012 for cars, trucks, and buses capable of running on nat-gas. Some of our Foolish analysts are enamored with the company's prospects and financial backing, and are buying up more shares.