I was monitoring my flight prices with kayak.com, it kept giving me stale results almost for a day. Flight prices given by kayak were horribly wrong. It kept showing $71 where the actual price was $161. I lost almost $100 due to wrong results given by kayak.com. And it kept showing me flights which were already full. Its better to search prices and flights on individual sites rather than trusting kayak. I know its time taking but you won't regret later like I did.