I have spoken to a friend who is a travel agaen, she said that when people go online just to LOOK at certain dates to travel the more people are interested in a certain day the price goes up. 50 people could look at 21st sept 09 and from that 1 books the price is higher due to the interest in that date. Sometimes the planes will leave half full and they dont care, they wont reduce prices to fill the plane. I looked at March 2010 and the 1st price I got for the dates I wanted went up when I went back to check them when my computer crashed, thats why I asked my mate and she informed me what I said above.