You can just get a regular hypodermic needle or go to your local feed store and get a needle for giving cows shots. I have even seen people using meat injection needles they are all just to deflate the air sack.
www.bendsmender.com But like Twilson said, any hypodermic needle or farm needle will do the same thing. Just take the "plunger" out of it so that there is a clear airway for the air to escape