You were smart enough not to buy car or for that matter, plane fuel as some uneducated LHS owners or employees would try to sucker you into buying whatever they had on their shelves to avoid losing a sale.
With Tower Hobbies/Great Planes you have a choice of saving money a couple of ways. The LHS can sometimes help with the Haz-Mat charges or shipping fees but you pay the sales tax. You can order it directly from Tower if you'd like. No problem with John Otto either if you want a blend made for your boat as he can do it.