Well, ethanol costs $2/gallon even at sky-high corn prices. At the moment the blendwall is around 16% (mix of ethanol with gasoline for fuel) due to the technology used in car engines. Isobutanol, a cleaner form of ethanol, can be blended up to 24% (I think). All you need essentially is to replace the current car engines to an ethanol/isobutanol friendly type (i think they are called flex-something) and they can use much higher % of the stuff. It already happens widely in Brazil, so it's not a futuristic idea. More importantly, both ethanol and isobutanol can be produced anywhere where you have feedstock that contains easily accessible sugars (sugarcane in Brazil, corn in USA), releasing you from Middle East oil. All that is feasible today, and is practiced today, and costs about 2$/gallon, which at a high blend with gasoline could probably keep prices under 3$/gallon easily. Once the advanced biofuels are here in large quantities, i.e. when the tech to use waste feedstock is refined, you will see even larger price savings. There are companies that have already demonstrated the technology to achieve that, they just need to scale it up succesfully.