My little sister is having a princess themed birthday party and I'm supposed to wear a gown, but I don't want to buy one.
That sounds like fun! Why don't you want to buy the gown?
I just don't want to spend money on something I'm going to wear once.
That makes sense, but sometimes we have to do something for the people we love. Your sister will love this party and be very happy. I know you don't want to spend money, but this would be worth it.
I guess so, I'll have to go gown shopping now.
I think you'll have fun. Try to check thrift stores and see if you can find one for a cheap price. You could also rent one from a costume shop and that would cost you less as well.