My Grandmother brought up this more expensive point too, They tried it also, and liked it.
The quart was $2.69, They said cow milk is like $2.39 a quart. I pointed our to her that S!lk stays fresh for much longer, mine was dated Dec12... So really she could purchase a larger container for a cheaper per unit price and use it MUCH longer than cow milk. So IMO, it is cheaper to buy S!lk.
We tested the red carton, it says Plain flavored (but sweetened w/ Cane juice) We're sticking w/ it. We were all suprised, it tasted like cow milk, except no slimy after taste. It tasted cleaner or something. You know foods that make you feel good, not icky inside.. Like that.