Where can I get a reliable and a updated Airport API or Airport Database, and I also want to know the charges for the API?
Location Identifiers &amp; Airline Designators data files available with daily updates
The perfect solution to feeding your coding database. These files (more information in right hand column) are available as a 12 month subscription or a one-time web download. For the subscription, you will be granted access to the password protected extranet site upon purchase where you can retrieve the data files update daily.

http://www.iata.org/publications/Pages/coding.aspx