Watch the school rental cost which is usually not included. You can buy bowling shoes for a decent price ($30 to 40)on the internet (try zappos) or try goodwill or make calls to friends and family.
Where I use to work (years ago), shoe rental was $3.75 to $4.25 depending on day/time.
Plus make sure to sign up your babysitters, so they can take the kids, too.