Was in a discussion with someone, and wondered what the thoughts were here. I usually choose my airline, go to their website, and book my flights. I have used Expedia (and Agoda, and one or two others) for hotels, but rarely (if ever) for flights. Today I had someone swearing to me that such sites (Kayak in particular) are cheaper than through the airline sites.This makes no sense to me. The airlines have to give the booking site a cut (at least I assume that's how they make their money), so are they really going to allow such sites to be consistently cheaper? If that were the case why would anyone book on the airline site? And so the airline would be paying commissions for every seat sold, instead of saving that expense by having folks log into their site. I would think they could undercut the booking sites by maybe 5%, and come out ahead compared to paying the booking site a commission.Comments? Experiences? Opinions?