I'm pretty sure Tim in Texarkana will sell & ship you any amount, but orders under $40 or so will have a handling fee($10 ?) attached to them. His phone # is on the site supporters page. M-F normal business hrs, ~8-Noon on Sat's. He's good guy to deal with, I drive ~70 miles to buy mine. Other Schaeffer sellers may also have no minimum order size, but I don't know who they are.
In Canada you can order smaller orders from Burkely. I ordered one case of the 10w30 blend
myself. I just wish it didn't cost me $32 for shipping though. To get free shipping I'd need to
order 9 cases, which is way too expensive for this poor boy.