A number of years ago I wrote up a business plan for a K-F museum. Considering that despite what some think, it would never pay its own way from admissions, etc so it needed to live off its own portfolio account. With today's rates of return on government investments (the stock market is too risky and so are hedges, bonds and mutual funds) that account needed to be worth around $20,000,000 to cover expenses with another $8,000,000 in start up costs.
When you recover from the shock, consider this. At those figures, the facility would own its building, cars and contents in general and even be able to accumulate cash annually in a building expansion and maintenance fund so it could grow if suitably placed. As a 501c3 it would also be able to give tax deductions for donations of
?? that qualified within the scope of the mission statement/charter.
Remember, even the Corvette museum in Bowing Green KY would be vacant and shut down today if it wasn't for a state tourism subsidy.