Where To Buy an Air Pass
Besides buying an air pass through a travel agency or directly with the airline that offers it, there are some travel websites that let you purchase air passes through them.  Here is out list of those websites. Note: You usually have to be a resident of, and coming from, a country outside the region or country for which the air pass is valid.

• An air pass consists of one or more flight segments. Each flight segment is a one-way flight between one city and another. 
• Some air passes may only be available if you buy your international ticket from the same airline or from certain airlines. Regardless, most air passes require that you have an international ticket and that ticket identification often needs to be part of the air pass ticket. Some air passes may stipulate which international airline can be used.
• An air pass may not be available if your international ticket comes from award miles or was purchased from a consolidator.
• Just like normal tickets, you may be charged for changing dates or your routing.
• Be sure to read the terms and conditions and talk to a travel representative if you don't understand something. 

Air Pass Websites by World Regions
Includes air pass websites covering many airlines and airline air pass pages
Note: You usually have to be a resident of, and coming from, a country outside the region or country for which the air pass is valid.