Join Mustang Club of America and you can get one almost instantly. (You should be a member if you are a true Mustang fan).
Don't tell anyone, but go to Fordpartners.com and enter mc405 as the code. You can then check prices on any car and generate a pin. Keep this quiet.
I am greatly concerned about the price. A premium GT right now can easily run $40,000. When the Mustang made its debut, it was very price competitive. I know if the 50th anniversay GT is $45,000 or more, I won't be buying.