Well, Lady Gaga is a popular singer, and I don't think she would be able to perform at your party, sorry. But if you CAN arrange it, I would imagine it would cost a lot to get a superstar to perform at your party. Maybe, judging by how famous she is and how far she would probably have to go to get to your party, I'm guessing 1 000 000 +. Good luck! Lol .