Birthday parties are so expensive!

My daughter is going to be seven on New Year's Day!  (She would have been the first baby born in NH that year if I had had my c-section when the doctor told me to!)   We usually have her birthday party the week after.  In the past, we've had her parties at her gymnastics facility, but we've decided to try something new this year.  My daughter chose a place in the mall where kids can paint a piece of plaster.  My daughter and I went to the mall this weekend to reserve the day for her party.  I was shocked to hear that the price only included 10 kids, including my daughter.  Then, for each additional child, it's $22!  I asked if I could supply the pizzas instead of them.  The answer was "no", but they will provide one for $16 EACH! Are you kidding me?  I never pay that much for pizza!!  I've been thinking about this for a couple days now - the price does include the goody bags and drinks as well.  But, holy smokes, this will be an expensive one!  Why don't they have price options and allow parents to provide their own food and drinks?  So, the big dilemma is whether to just invite my daughter's girlfriends or whether to invite the boys as well.  My daughter has several boys in her class that she is good friends with and has been invited to their parties as well.  What to do...what to do...