If on Expedia you don't pay any booking fees etc. what are the chances of your fare going up? I would not want to pay $30 for a fare that is unlikely to change and if its not confirmed I pay this fee. It would make sense to pay this fee only if I knew the fare would go up. 48 hours is usually not enough time for the fare to change but this is where ExpertFlyer comes in handy. If you have Expertflyer you can tell if W Class has 40 seats or 3 seats then I would book it right away if ExpertFlyer showed W 3 and I needed 1 ticket.