What should someone who is on a budget can only invite a few people and who is turning fourteen should do All-girls no guys so dancing and stuff is out. It's going to be small so nothing big?
You should then do something interesting--have several choices available. Maybe go retro?? Make taffy or ice cream. Try a new game that everyone can play--try to put the phones/texting away so everyone is with the program. Rent a few movies so there is a choice. Have delicious snacks...make punch rather than serving cokes and energy drinks.