How to save on baby formula.

Hi ladies.

Please share the ways to save on baby formula.

I am breastfeeding mom but still after breastfeeding my son asks for more. He's got good appetite. Dr asked us to give some formula.
and now for every feed he takes formula and bm.

I have registered and got a sample of formula at branded companies and also got a sample at the doctors office.

Are there other ways to save on baby formula.