I'm looking at this from a completely financial point. Initial cost of set up will cost you the most, after that, you will get of cheaper, but I still don't see it as being close to what you pay now to breed yourself.

Initial set up cost of tubs and equipment.

1 tub for breeder mice
1 tub for females after weaning
1 tub for males after weaning

3 52 qt tubs from walmart I believe was 5$.

$15 for tubs

1/4" hardware cloth 8$

3 water bottles and hides
Depending on brand, 6-8 ea.
24-38$

Total so far: 47-61$

Now food costs, what size and brand of feed will you buy?

Mazuri 9F is an excellent food choice and available from most Purina dealers. I always recommend giving your animals the best feed, the best that goes into your rat/mouse will be the best in your snake.

Kaytee brand is mostly crap, as well as any mixed feeds (seeds, corn, colored kibble) For breeding mice, I recommend a nice lab block to use in a hopper for the mice to free feed. Less waste and you know it is a good food source and complete nutrition.

Mazuri, small 3 lb bag from petsmart costs 8$ here.
A 40 lb bag of Mazuri 6F from my supplier is 22$ Make your own decision on how much you want to buy compared to how much you will use.

Total so far: 68-83$

Bedding, aspen is best. No cedar, or pine, it is poisonous to small animals and especially for your snake.
Aspen bale is 12$ from petsmart, and will last you a long time.

Total so far: 79-94$

Then, cost of mice. 2$ each.

83-98$ Total.

This is for the initial set up cost that you wont even come close to spending in 3 months of just buying your mice from the supplier.

I'm just estimating with all of it, considering I raise only rats, and they take a dent out of my wallet every week, but it is actually better for me to breed my own. It would cost more or less however you decide to do it.

Edit: I also really like Becky's system, she's got it down