This hsppens all the time. Most airlines only release a certain number of seats at the lower price, in this case might be 3. Then after those seats fill up, you get pushed into the next fare tier, which in your case is $30 more per ticket. When trying to book airline tickets, all tickets purchased together have to be in the same fare class, since there aren't enough "cheap" tickets left, you and everyone in your party get "bumped" up to the next fare class. You could try to book 2 sets of 3 tickets, but my guess is that the second set will be more expensive then the first set, and might be GREATLY more expensive since the airline computers sometimes raise fares once seats have sold on a flight. It happened to me when my sister and I were trying to get on the same flight. She booked her tickets first, for $225 pp. I went on about 30 minutes later and then tickets had risen to $350 pp!! YIKES!! Well, I held off for a few days and then fares did drop back down to $250 pp and I bought then.