Airtours and other charter operators will never offer you the BEST deal on tickets. With the dollar being weak, you are far better off buying your tickets from a reputable US firm BEFORE you leave. Mapleleaf offer a great service and will almost certainly beat any price offered by Airtours.
If you decide to leave buying your tickets till you get to Orlando, research the "book price" of the tickets, so you know if Airtours are offering you a good deal or ripping you off. You can buy tickets at Official Orlando Tourism outlets for a discounted price.
You can sometimes be "lured" to Welcome Meeting by the promise of free tickets or incentives but they are rarely worth the hike in prices of the tickets you REALLY need!
Also, dont buy too many passes...its easy to get carried away booking tickets and excursions! Plan carefully and know exactly what you want before you part with any cash!
Good luck!
Allie.