i had a friend, who's way into cars, tell me that all gas is pretty much the same. the differences came in where each brand adds there own special mix. he told me that he knew someone that worked for one of the refineries like shell or mobil. he went on to say there were a group of different companies all in the same location like shell, mobil, exxon and they frequently bought/sold gas from each other.
not sure i'd buy from a no name brand. i use this site as my gauge and just find the cheapest high octane on my trips:
http://www.gasbuddy.com/