The cost of cans has a couple of barbs. For Sun King in Indy and other craft brewers, the biggest problem is that they can't just slap a new label on their stock of bottles when they want to push out a new seasonal or specialty. They usually have to buy a gazillion cans printed with the new beer's labeling. That makes it far less appealing to have a canning line if you want to be creative and put out small runs of beer. In the case of SN, they have 5 beers that are constantly brewed and another 5 that have big enough production to use cans too.
If I understand correctly, Sun King has been allowed by the ATF folks to create a generic Sun King can that they can apply another label with the actual beer's info. That might make this can issue more appealing for craft brewers with smaller production. I haven't seen any of these labeled cans on the shelves yet, so I don't know that its a reality.