I didn't see the Black Muse in Large on display at NM Beverly Hills yesterday. I saw the White Muse in Medium (til store closing), that's why I'm pretty sure it's still available (hopefully, Sweetsparkle will be able to get it). I only asked the SA to check for availability of the Medium Muse in Chocolate/Tan (all sold there).
NM Fashion Island carries YSL, but they are all sold out of the Muse (all sizes/colors) a few days ago. You can ask a SA to do a stock-check for you, maybe their San Diego store might have it still. The bag can be shipped to you directly or be transfered to your local store.
riana, you should check out SoCal's auction. The link can be found a few posts above this one. It ends today and the bag is currently going for below retail. You can find pictures of the bag in her auction.