C.S.
We had my daughters party at Metzlers Gymnastics in Downingtown, just off of Route 30 after the shopping center with BJ's. They have a website think it's Metzlersgymnastics.com, google it just to be sure. They let you bring food and invite up to 12 kids for about $150...I just took cupcakes, juices boxes, popcorn and the little dixie cups of ice cream. It was just enough and the kids liked it, i had it at 1:30 so the kids should have eaten lunch. My dauther just turned 8 and her and friends loved it.
I also did build a bear at the Springfield Mall but I had limited it to 5 girls plus my two children and increased the price some, they had a discount if went a little higher. Then I took them all next door for ice cream only at Friendlys...they liked that too.
YOu could also look at the Y in West Chester or I think there is once in Lionville depending on where you are. Good Luck and have fun!