That's the nuisance with Amsoil... it's sort of a pyramid-style marketing scheme, sort of like Cutco knives. Good products, but the marketing may turn some people off.
Anyway, you probably will NOT find Amsoil at any major chain stores. A smaller local speed shop may carry it. If you intend to buy more than a case or two at a time, you can probably get your own Amsoil distributorship. A couple of years ago I investigated this and found that may be the cheaper way to go, unless you can find a local Amsoil dealer that sells near wholesale prices. Do some Googling and see what turns up... that worked for me last time.