Bob and Bryan,
SIG still sells "Bakers AA" in qts and gallons - gallons being better price per fl oz.
KLOTZ may still offer their racing castor, which they assert is refined (filtered?) beyond what they get as raw stock. Can't comment on pricing.
Castor oil is not a flammable, and is not a volatile liquid, so HAZMAT likely does not come into the picture.
AMSOIL might have a usable racing castor - their products apparently have street cred in auto/boat (people-sized) high-performance uses. 'net search on AMSOIL should find their catalog. They usually have local dealers you can find and buy from.
As with most anything, buying in larger quantities usually might find a better price. (Not in grocery stores - take a look if you doubt it...) So, depends on whether you are brewing up sizable batches of fuel from raw ingredients, or just 'sweetening' a commercial glow fuel blend.