We are going to Costa Rica this August, so I bought 6 plane tickets today. Here’s something interesting… if you book 1-4 tickets, they were $439 (plus tax/fees), but if you book 5 or more at once, all the tickets were $702 (plus tax/fees).
So the tip of the day is… just buy two different blocks of tickets if you need to. Then they are all $439 (in my case). 🙂