Well, UT Southwestern’s mouse facility charges 75 cents per day per cage to house and feed mice in a barrier facility, and you can house 5 mice per cage as per the IACUC crowding rules, which brings it to 273.75 dollars per year per 5 mice, so if it were a ~100 mouse experiment it would be $5475/year in costs of housing the mice. Depending on the strain in question, you can obtain them from commercial or in-house vendors for between $20 and several hundred dollars each, or breed them yourself at the low low cost of at least one month of your life (and the frustration when they do things like eat their first litter or drop dead for no apparent reason). Assuming you’re using cheap, wild-type mice at $20 each, that’s $2000 to get your subjects.
Then there’s the university overhead costs for any funding received (typically a large double-digit percentage, 50% is not uncommon), and the salaries of the people doing the work itself. A typical grad student costs a lab about $50,000/year in tuition, stipend and health insurance. Lots of institutions also only directly fund a certain percentage of PI salary with the rest covered by soft-money from grants to incentivize bringing in the grant funding in the first place. The mice themselves are a relatively small part of any experiment– the money to pay for personnel is going the be lion’s share of the expense. Call it $100k/year for the PI and one grad student plus ~$20k/year in reagent costs and the mice themselves, then double everything for overhead costs, and you’re right there at $240k/year. If you’re shooting for the M prize and you want the mice to live 5 years, now it costs $1.2 million.
This does point out that since the people are the biggest costs, it would be very efficient to have one lab perform many life span experiments at the same time.