I'm having a birthday party in December and the theme is comic book characters. We need to find a place to have this party at that is cheap and semi big. We are having about 15 to 25 girls over.
If you belong to a church, start there. If the weather allows, use a public park. Sometimes these parks have a community centre. YOu could also inquire at school.
Some co-ops, condos and apartment buildings have rooms. Churches and libraries will sometimes let you use a room for free. If not, a pizza place can have a party room at a reasonable price.