It isn't really possible to give round figures on the cost of producing your own feeders. There are too many variables involved.
How big of a colony? Just mice only or rats and mice or rats? Cost of wood, tubs, bedding and food in your area?
If I recall correctly you have larger snakes such as the rainbow boas. Unless you have snakes that consistently need smaller than rat pink sizes, I would suggest just breeding rats. They don't smell as much as mice. Male mice have a strong musk in their urine so you will always smell that musk, even if you just cleaned all the cages an hour ago.
Male rats don't have that smell.
Depending on how big your colonies are, how small your tubs and how frequently you change the cages, will determine the overall level of smell.
I only have a small 1:2 rat colony which keeps my 9 snakes fed but these are adult snakes which I only feed every 10-20 days. Non adult snakes I feed once a week. I don't remember the size of your colony so a 1:3 colony may be what you need or multiples of 2:1 or 1:3. (thats one male to two or three females.)
I don't use racks for my rats for obvious reasons (one cage rack isn't very useful) but I like to give them lots of space so I use the large Rubbermaid Roughneck tubs which has plenty of room for three to four large adult rats and several litters of babies. I also find it isn't necessary to clean the cage as often. When babies have their eyes open the smell does tend to build up faster so I change about once a week.
As you plan to sell excess find out how many you are likely to sell, if you only have a few friends, then I would not produce more than a few colonies more than what you need for your own snakes and build from there.
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PHLdyPayne