IIUC, the airlines themselves operate on a totally flexible fare system. So unless they're willing to commit to a given fare on a future date, how would you do that? I've gone onto a airfare sites, got a price, thought about it for a bit, and found out it was gone when I finally went to commit.
A travel agent (who may be wrong - I don't know) told me fare quotes were usually only good for about 10-15 minutes from the moment of request - and were constantly updating and fluctuating in the background because the airlines were juggling them in real time based on actual bookings.
Does anybody know if that's correct?