I'm not in the business, merely a hobbyist so take my points with a grain of salt, but here are my thoughts... and pardon the discombobulation of this post. It's almost 1 am here and my brain is fried for the day!
A couple of things to consider in your start up costs:
- possibly flooring
- possibly specialized insulation
- caging and thermostats
- possibly a misting system if you decide to go that way
- a utility sink w/ an attachment for a hose (use the hose to go around and fill water bowls)
- possibly a restaurant quality dishwasher (good investment if you intend to have 850 babies/juveniles/sub-adults) plus 18 adults. Look into a used model to save quite a bit of money.
Caging for 500 babies would best be accomplished with something like a freedom breeder rack. You'll need 7 at $2,889 each as they each house 75 animals. $20,223
Caging for 300 juvies would best be accomplished with freedom breeder racks as well. You'll need about 9 (rounding down) as they house 33 animals each at $2,299 per rack. $20,691
Caging for up to 50 sub-adults - freedom breeder once again. You'll need two racks that house 30 animals each at a cost of $2,399 per rack. $4,798
Adult caging for 18 animals of various sizes. Assuming some will be larger, some will be smaller, we'll go with 2 48" wide racks with 6 levels each for males and smaller females. $2,120. And one rack that's 66" wide with 6 levels for the larger females at a cost of $2,521. Total cost for adult caging: $6,761
Water bowls - more expensive than you think. But, buying in bulk would probably allow for a substantial discount. You'll need 2 bowls for every cage because opening each cage, removing the bowl, then washing it and replacing it will cost a TON of time. So, 1,732 water bowls even at $1 each (which I think would be a good deal) will run about $1,732.
Substrate - cost will depend heavily on what you use. And, this will be a recurring cost. $Variable
Rodents - best bet is to breed your own. This will cost money to start (breeders, racks, watering system, substrate, food) but will pay for itself many times over for a collection that large. Rodent breeding racks (freedom breeder again) for mice are $2,000. You'll probably need just one. You could supplement with a rodent supplier for any shortages unless purchasing another makes sense. Same with a rat rack at $1,615. Total for rodent housing $3,615 (conservative I think as you may need more caging for more rodents). Add in the watering system (lots to total up and I'm not doing the math so a guesstimate is) $500. Variables are cost of breeders (go high quality so expect to pay a little above average), substrate, and food (again, high quality). Total cost is $4,115 plus variables.
Thermostats - herpstat pro is the best, IMO. $300 each and they have 4 outputs. A total of 5 for the babies, juvies, sub adults, and adult male rack (one output per rack) then 3 more so each female has independently controlled heat. 8 x $300 = $2,400.
Flexwatt is relatively cheap. You can probably buy everything you need for $500.
Then, supplies. You'll need things like spray bottles, hemostats, pinky pumps, tubes, syringes, mite spray, bleach, Nolvasan, etc... Let's guesstimate $1,000.
Tax and shipping hasn't been included in any of these prices and I'll leave them out and use those numbers as your "volume discount" that you'd likely get (probably conservative).
Total with just the things I thought of off the top of my head is: $62,220
Who knows how much it would cost to design everything, run proper electricity, a back up generator if necessary, permits (look into this), a website, staff (unless you plan to work 24 hours/day every day), phone, computer, digital camera if you don't already own one, office furniture, dishwasher, utility sink, a couple of freezers, etc... My guess is your $100,000 is tied up in start up costs before you even get around to buying animals - if you go with high quality "tools of the trade". You could probably shave off a substantial amount of money if you bought second hand racks, etc., or just cheap imitations - but still probably not enough to get it down to $50,000.
Then, you get into animals. Are you buying adults and hoping they'll produce for you, or buying babies and raising them? Whichever you decide on will impact the quality you're able to purchase. Adults = lower quality as adults usually go for more money. On the flip side, buying babies = no income for several years (which may be ok if you want to raise them at your house and put off the separate facility for a few years while you raise your 18 breeders).
Personally, I think you overshot the number of animals substantially, unless you plan to buy other people's animals and resell them. Room for 500 babies would mean that ALL of your females produce every single year and produce, on average, 42 babies each that live and need housing. Personally, I think production at 30% of your females per year would be good as you'd be best served (as would the females) to breed females every other year and not every female produces when bred. And that's assuming 20 babies per litter which would be fairly good. I think you're looking at around 75 babies per year. With numbers like that, $50,000 start up costs for the facility is EASILY attained. But then, that probably messes up your $30K profit you were hoping for.
So, that's the way the numbers work in my head. Hope it helped!
Good luck David,
jb
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What's written above is purely my opinion. In fact, MOST of what you read on the internet is someone's opinion. Don't take it too seriously 
Jonathan Brady
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