Michael King makes an interesting point about supply efficiencies on his blog:
Gamblin Cad Red :: Mmmmmmmmmmm, yummy!!! I wish all manufacturers offered their oil paints in cans. Gamblin bucks this trend and lucky for me, I enjoy Gamblin paint and find it of high quality at a very good price. Every acrylic brand you find in your local art store sells their products in tubs. Wander down the oil paint isle, though, and you won’t see any cans of paint. Gamblin sells all their colours in 8oz and 16oz cans. Their whites are also available in 32oz cans. The caveat? The chances of your art store carrying these cans are slim to none.