I got my from Duncan Direct (I think the same as Van Dee), they said it only comes in 1 gal or larger quantities, the reason is so they can classify it as "indurstrial use only" for legal reasons.
Since using it, I would not use anything else. Very easy to use, just follow their instructions.
My bows haven't been around 20 years to crack/fade, so I can't comment on that. But they look great and, AND, the stuff is very tough and supposed to be solvent resistent after curing.
Important? Handle a bow after putting on sunscreen and you'll see why.
Dan