I have one ball at the moment.

I tried a breeding pair of rats to offset my cost. In 6 months I have no babies rats and 2 new pets lol.

I now have a harem of 3 lady mice and a little white stud. If you rotate it out right and keep good logs, you can plan your breeding so that your snake eats and you are not overruned with rodents. You will spend a little chunk to get up and running. I would say I may break even after a year or so of investment. The biggest cost is food and bedding. I got a nice tank with a mesh top from goodwill and picked up a bottle and wheel (build those delicious haunches ) offline for probably $20 shipped. I buy a bag of lab rodent blocks for $2 a pound or something from my local pet shop as well as a brick of pine bedding every few months.

If you have access to live feeders close by or if your buddy will eat frozen, its by far cheaper and much less of a hassle. I like raising my own for the peice of mind knowing my snake is chowing quality. And the mice are pretty cute too.

But I now essentially have 2 pet rats and 4 pet mice that take up garage space. Keep that in mind. Also, mice STINK compared to rats. I love the rats, great animals. Smart too. Mice, not so much.