One place you can go and get just about anything is
Dion and Sons. We deal with them here at my work for oils, but they also carry many different brands of race fuel and many different octane levels. They have a couple different locations, but I cant find them for some reason. They do a lot of stuff for races in F1, Irwindale, and Fontana I believe. FYI, they aren't a gas station, so you can only get it in containers.