I'm pretty sure ATPCO is the only way to get the raw data; people who subscribe to it are not allowed to redistribute it. As for getting processed data, that's

I'm pretty sure ATPCO is the only way to get the raw data; people who subscribe to it are not allowed to redistribute it. As for getting processed data, that's called metasearch: scraping other sites' search engines. Kayak started out as pure metasearch, but moved to using ITA. Not sure whether they still do any scraping.