Scratch that. Kayak said there were 4 seats left, and I thought that meant just at that price, but there could be more at a higher fare class. Nope. As soon as I pretended that I wanted to book for 5 people, that option disappeared. Thankfully I was able help them book a confirmed ticket on UA with my 20% discount so it's fairly reasonable, especially considering that it's booked less than 24 hours in advance.