Hi, Katy!
I'm guessing what you got is a "Pin Code" with the discount offer. You can certainly hold out to see if you get another Pin Code or if there are any
Special Offers, or you can go ahead and book and if a better deal comes along, you can call Disney to see if you can apply that offer to your vacation. Currently, there is a "room only" discount for stays through August 14, 2012.
The "Pin Codes" are not very common so you may not receive another one, especially in time for your Fall vacation. These only go out to random guests, so you were just one of the lucky ones this go around!
Good luck, and I hope that between the
Special Offers and any Pin Code offers, you will find the perfect vacation for your family and your budget!