I rotate my own curriculum and supplies. I have TONS, and when I find something inexpensive off season I can add it to my box then. Saves a bunch.
I no longer do paper anything. Ink was a HUGE expense.
No batteries.
No transportation.
No field trips.

I'm also trying to create a meal plan that is nutritious and cheap to make.
For instance, when hams are on sale I buy one, my family eats, daycare kids get a meal, then I cube the rest and make either split pea soup, ham & potato soup or ham and beans it's enough for my family and daycare, plus we get still have leftovers for scrambled eggs or omelettes with ham.