I've got three colonies set up so far: a 1:7, a 1:7, and a 1:4. On any given month, I've got over 80 pinks being born and various numbers of other sizes as well.
Price of Required Things:
I house mine in aquariums. If you're going to use aquariums I would recommend what is commonly referred to as a "20 gallon long". It's a 20 gallon tank that is longer than the average 20 gallon used for fish, and is primarily a reptile/rodent tank. At my local Petsmart, a 20 gal long will run you around $30. I use ESU wire mesh lids, as I find they're a lot more secure and resist chewing. They're entirely metal and the wire is very sturdy to hold up to a 20lb cat sitting on it for over an hour (don't ask). =P The lid runs me around $15 for that size. Or if you can find the 20 long with the built-in sliding lid that locks with a pin, that would be good too.
For bedding I buy a large bag of Aspen shavings for around $9. It lasts my 3 colonies and my multiple snakes for over a month or so. Here recently I've been testing out Aspen Supreme Pellets, and so far I like them. It's been 2 weeks since I last cleaned them out and I smell nothing so far. It was around $7 for a 10lb bag. But it does come in larger bags as well, my Petsmart just doesn't stock it.
Water bottle holder is around $2-4 depending on brandname and the bottles themselves can be bought at Walmart for $1 or the cheap SuperPet brand at Petsmart for $.80 (the ones I use).
The food, I buy from a local feeder breeder who gets it from a feed mill that specially makes it for him. I buy a 50 lb bag for around $13. This lasts my 3 colonies for 6 months or more. Or you can buy the blocks from other makers in a pet store. If you choose to feed seeds, I would recommend one that doesn't have sunflower seeds. They're all fat and no nutrition and you end up with mice who laze around and don't breed. The last time I bought L & M brand blocks it was $10 for a 5lb bag. Mazuri is also a good brand I've heard.
The mice, their price depends on where you get them. If you buy them from a large chain store, expect to pay around $5 each. Pretty hefty if you ask me. If you have a pet store with good quality "pet" mice, they should run you $1 to $2 each. Just make sure you don't buy the feeder mice from the back room and expect them to do good. Most of mine ended up dying within a month and never had good quality babies. They're feeders for a reason, I've found out. Check the local papers for mice, even in my little ole hick town I've seen them for sale every now and then. Another good source is schools. Elementary schools breed rodents in the classrooms, just ask to buy any extras if they have them.
Now to break it down:
Cage: ~$30
Lid: ~$15
Bedding: ~$8 (price between Aspen Supreme Pellets and Kaytee Aspen Shavings)
Water-bottle: ~$1
Water-bottle Holder: ~$3
Food: ~$10-$13 (block diet)
1:5 mice: @ $2 each ~ $12
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Total ~ $79 for the initial start-up. That price may vary depending on where you get your stuff and mice.
Care and husbandry:
~ If you keep them on aspen shavings, expect to clean once to twice a week. The more humidity you have, the more often you have to clean as it keeps the urine fresher and potent. Dryer conditions allow the waste to dry out quickly.
~ Never ever ever use pine or cedar shavings. The oils in the wood is toxic to small animals.
~ Ventilation is key. Mice and rats are susceptible to their own waste fumes (ammonia). If you don't have good ventilation and fresh air, expect to see a lot of respiratory infections. Sick mice don't breed well.
~ Rubbermaid type containers work in a pinch. But they hold in the moisture and odor, so you increase the amount you have to clean them out and you also increase their exposure to ammonia which has a detrimental effect on the overall health of the mice. Not enough ventilation to be any long-term enclosure.
Other tidbits:
If you have just a handfull of snakes, it may or may not save you money. But when I got past the 10 snake mark, it helped me immensely. I always have a steady supply on hand of the size I want. If a snake decides not to eat one day, I don't have to throw it out, I just put it back to grow up to the next size and use it some other time.
If you can give me how many snakes you own and what they're currently eating it'll be easier to give you an answer as to whether a 1:5 would be too many. To me, I'd rather have to suppliment my supply with f/t than have too many and waste them. I started out with a 1:5 and as my snake population grew, I added colonies and mice as I needed.
When starting a colony, I've found it's best to get all of the same age group if possible. But if that's not feasible, I usually aim for an older male and younger females. When I add a new male to older females they have the potential to castrate him. When they get in fights, the place they inflict the most damage is the testicles. And of course those are kinda vital to breeding mice, wouldn't ya say?
I've not had any need to separate the females from the group when they give birth. Usually all of the other females share in the mothering responsibilities of feeding, cleaning, and keeping the babies warm. Initially you might want to watch the male, as new males not knowing if the babies are theirs, will kill the pinks. If you see that happening, just remove him till the babies are used up. But most of my males will share in the housekeeping of the babies. I even have one that tries to nurse the babies, and if one falls out of the nest, he'll pick it up and put it back. So it's all really individual on their part.
When you get babies, just remember to keep the water bottle filled at all times and food present at all times. Nursing takes a lot of energy and nutrition away from the mother. And if conditions aren't at their optimum, they'll cannibalize their own babies.
I hope that helps you a little bit. If I think of anything else I'll add it in later. Or if you have any questions, feel free to e-mail me. =)