Millennials plan to spend more than any other generation for the holidays, a new survey says. But using credit cards or payment plans may come at a high cost.

According to the travel site Kayak, flights are 6 to 9% cheaper than last year, but the window to find deals for Thanksgiving, Christmas, Hanukkah, and New Year’s is closing quickly. Travel experts warn that airfares will jump 5 to 10% every day during the last two weeks leading up to Thanksgiving.