I would like to integrate in my web site a flights search engine. I am wondering how can i do this. Who sells this kind of service? or there is an elegant and easy way to this?
ps: of course i need the possibility to books the flights.
FlightStats has an API that may serve your purposes, depending on your use case.
(If you want to do bookings and such it won't help you there, but it will show you flights for the next several days, as well as data for flights in the air).
If you need information for bookings, you're pretty much stuck going to Sabre.