As a mom of 3 I also agree to keeping it to 10-10:30. Past that time odds are your going to have some VERY cranky/ hyper kids. What will you do when the kids start falling asleep? While some kids can stay up until 12 I think it'll make for a hard situation. Pricing would depend on the state your in. In Cali I've paid 30-40 at a really nice gymnastics center. Since it's at a church and your first time doing it then I think your pricing is low enough that it would make people give it a try. Good luck.