Hey Carlisle,
If you want a cheap and good food for ASFs try lab block 5012. It's made by purina and is superior to anything I've ever tried.
I've tried: dog food, cat food, bird seed, mixing my own foods, leftovers....this stuff is way better.
Within a couple months of switching I noticed that the rats were already having bigger litters then I've ever recorded. They were taking care of all the pups in the litter. The pups were reaching size much quicker then before. All around better fOod.
Also the stuff comes in blocks so it is perfect for food hoppers! It costs me $30 a 50lb bag in Ontario.