This site is the maximum you should pay, as its what travel agents & aggragators pull data from. I've regular found cheaper flights from onetravel.com, but I use the Matrix site to find flights (for years now), as all available flights & code-shares are usually on there. Some rare exceptions. I normally flight to/from or in Asia and any airline I care to fly, except for a few that only sell on their own website, are listed on the Matrix site.