Cost effectiveness of raising feeders

[hobbyist]

Yesterday I paid $6 for a rat for a new BP I just received
So I have a question for all of you more experienced with reptiles and raising feeders.
I have 3 BPs right now, and will keep the hatchlings they breed next year. I am considering breeding feeders, and want to know the cost of this before I start. There are many helpful threads in ASF, RATS, MICE, and OTHER FEEDERS, but I didn't find a specific answer to this question:
How much does it cost per rat (normal or ASF) per month? And how many babies can I expect of feeding size per cost of feeding the rats? I believe I read they eat .83 lb of food a month each, and at $28 for 50lb bag, I think 4 females and 1 male would cost
5 rats * .83 lbs= 4.15 lbs
4.15 lbs* $0.56/lb =$2.32/ month to keep 5 rats.
If gestation is 21 days, and about litter of 7 (or 10 for ASF), assuming 2 rats become preg, it should be 14-20 babies every month, and I don't know how fast they grow up!!
So here is where I need some help from the pro's. I want to euthanize and freeze them between weanlings and medium size, so does this take a month? two?
if one month: 20 rats ~$9.28 + $2.32(breeders) = $0.60 to raise each rat ready as a feeder! compared to $4 at local pet store.
If two months: 20 rats ~ $23.2 (including breeders) =$1.16 to raise each rat to feeding size.

please- this is all speculative math: I wanted to see how much it really cost per rat, and how long it takes for baby rats to grow to weanling size, and how long to medium size? Do they eat more in this time? Does it take longer for ASF to grow to the same size? I would rather keep them because of the smell-- how long does it take an ASF to grow up?

I'm not at all worried about being overrun- because I am feeding the others F/T and it sounds really appeasing to have an unending storehouse of cheap frozen food for them. Plus I could separate the colony if it becomes too much still. I have all the materials, so start-up costs are not a factor, and I read somewhere that you can use shredded newspaper as a substrate, if you are willing to change it out more often.

Thank you all so much for your help.