you can call MAC and see if they can do a warehouse search for you. They ask you to pay for the item up front and will ship it if they locate it. if they cannot find it, they will refund you.
sadly i am still waiting and wanting this brush! i have seen it in some sales threads of specktra however sometimes the seller is asking for a very high price - i dont like paying much over retail because i dont think it's fair. you can try ebay but there are so many fake brushes it is hard to find a real one! good luck!