You could switch to F/T and get them from rodent pro in bulk which would be your cheapest option.

But if you are inclined to breeding your own, then for one snake you really would only need 1 male and 1 female. Have 2 separate containers and pair them for 3 weeks, then remove. Once the female gives birth let her raise them for 3 weeks, and wean them.

With what I said above, you'd average about 8 - 16 rats each time, which would give you plenty so the momma could take a break before you breed her again. The only thing is you wouldnt have small size for more than 2 months because of the time it takes for pairing, breeding, and weanlings growing to small size. Another issue you might run into is the babies growing too large before you have a chance to feed them.

As others said, it just doesn't make all that sence to breed your own rats with only one snake, but it can be done.