I breed rats. Here are some numbers for ya to crunch!
I feed 5 BPs, once a week. There's also my BCI, but he eats thawed and I freeze my overproduced rats for him. We will count him out for this post, and the numbers will still work! Read on:
Buying live rats is necessary; three of my snakes will have nothing to do with f/t or even prekilled. So for my smaller-rat-eating snakes, that would be 5 times $4 per rat per week, which equals $20. Bigger rats for my adult BP would be $6 each! So if I bought frrom stores, it'd come to $26 a week for live rats.
I buy a 50# bag of rat feed, which costs $25 and lasts for 6 months. I buy bedding twice a month, if that. Bedding is $7 a bale. $14 a month for bedding.
All in all, the result is, it is much cheaper for me to breed my own. It costs me $40 a month to raise the rats... versus $84 per month to buy live! This is not even counting the large excess supply that I bred and sell to my local pet store.
So breeding rats can be economical. And if it takes me 15 minutes to clean out their cages every 5 days, so be it! But if you absolutely hate the presence of rats and their daily feeding/watering regimen (which takes me three minutes, 2x a day) then don't do it. And if your snakes are little angels who will eat f/t, then go that route!