I want to start a travel agency business , how do I get cheap air deals , how to buy tickets wholesale ?

You want to start a travel agency business first you need to apply a travel agency license then registrar as a company or cooperation.It is not easy to obtain a license because travel agency involve a lot of money.Once your get those then contact to airline co and open an business account then you will obtain wholesale price on tickets and become a ticket sale agent.

You sure? There's lots of better businesses out there. Have you been paying attention to all those Orbitz and Travelocity ads on TV? Those guys are web-based and they get millions of visitors per day, they can live on $10/ticket margins. Can you?

May I suggest a slightly different approach, like being a package tour promoter?

Anyway, check out the IATA:
http://www.iata.org/index.htm

To be a travel agent and get commission / discounts, you need an IATA number.
http://www.iata.org/whatwedo/passenger/travel_agents/index.htm