Babysitting can be expensive. If you have neighbors or friends with children of similar ages to yours, work out a babysitting schedule, where you can trade off a date night evening or even time to go grocery shopping. If you're going out with friends, ask your babysitter if they are willing to also watch your friend's children, it will often result in a lower amount per child to be split between you.
One neighborhood organized summer day camps by each parent taking a week of "vacation" and taking care of all the neighborhood kids saving thousands of dollars.