Park Avenues are typically only on sale during the Anniversary sale in July. If you cannot wait until then, I would pick them up from Brooks Brothers on 12/26 or get seconds during one of the seconds sales.
If they restock the same patterned suit, then yes the SA can do that exchange. SA has no discretion on this with regard to suits/styles that are new to 2014. Even if they look similar, anything that makes it new to 2014 leaves you out of luck.