That seems to work out to around 25 cents per 12 floz which is not a whole lot cheaper than the cans from costco.

A four pack of two-liters is $4: http://www.samsclub.com/sams/coke-4-2-liter-bottle/prod96004... which is 18 cents per 12 floz.

But it takes up less space, you don't need to resupply as often, and you can set the mixer on your tap to add more or less ratio of syrup to water.