OP what color are you looking for? There still should be some inventory out there and your dealer should be able to swap with another.
For example there are 4 mustangs on the lot at the dealer near me. One black GT and one in sterling grey, and two v6's ruby red and black.
2011 V6 Mustang - Premium 202A Spec (Pony Package) - SOLD!
2014 V8 Mustang - Premium 400A Spec
6 Speed Manual, 3.31 Rear
Black, Charcoal Black
Comfort Package, Security System