I know you are leery of buying on ebay but this seller, ellareese, has a black legacy shoulder for sale. She is AWESOME - I bought a 2006 legacy hippie from her and it is BEAUTIFUL. I would definitely check her out - and her stuff is absolutely authentic!! I was looking at the bag myself - but got the new shoulder bag in Clay instead.
You can always use the PF's authenticate this thread for ebay purchases. They are very helpful for people bidding on ebay.
http://forum.purseblog.com/coach-shopping/authenticate-this-coach-21893.html
Other than that, maybe call Coach and see if there are any left in the system or check some outlets.