$500 is not too much

Last year, my DS went to the senior/junior prom as a junior. He paid the limo and prom ticket, on top of his own tux rental and flowers. he spent over $300.

Ask your DD how much is her shoes budget and make up budget. Ask her if her date has agreed to buy the limo and prom ticket. Once she realizes the dress could be less than 50% of the total cost, she might consider a lesser dress.