The courier isn't discontinued, just not as many places are carrying it (which may not be a good sign for it sticking around). Barneys had some old stock. Be sure to ask for the dimensions as some of theirs are the larger (extra)courier. Have you tried hgbags? She carries them, if they're not all spoken for but I don't know what colors are available. Here's the link to her eBay store (I hope this is okay, mods?)
You can send her a message through eBay and ask if she has any or is expecting any. Good Luck!
Gretta Luxe always orders couriers, just not a lot of them. I know at some point they had anthra, black cherry/crimson, maybe argent, too. I got so accustomed to BALNY not ordering them that I haven't asked lately whether they are ordering from the current collection. They seem to have finally sold off their 2006 stock, so maybe?