I've seen cases where Expedia was substantially cheaper than the airline. I booked a $1600 biz round trip BOS<->BOM. The exact same ticket was at least twice as much if booked directly with the airline (not UA in this case). In this particular case it was a "package" booking and I needed to also book a $5 throwaway hotel in Mumbai. I'm still confused where these massive price differences come from. I very much prefer booking directly with the airline but 30%-60% discount is nothing to sneeze at. I've seen substantial savings with Expedia, Orbitz and Priceline. Not ideal, but certainly workable.