We get a bunch together annually and take a trailer to the S&K outlet in Tatamy, PA. I think 10% was like $11 a gallon last time (and I hope we do it again soon as I'm about out). It doesn't pay to buy more at one time than you'll use in two, maybe three years if it's stored well. It will go stale.

It's also good to support your local hobby shop . . . especially with things that have high shipping costs and fees. ;-)