Oh that is the cutest coat - Tila would look adorable in it!
Here are a few I found - (thought I'd list them all in case someone wants a smaller size). It
appears that Hot Whiskers has a medium - it's probably best to email them to be sure. I suspect a lot of these sites haven't updated yet and could actually be out of stock. Anyway, good luck!
Funny Fur S - $43.99 Posh Puppy Boutique XS, S - $70.00 Sassy Pup XS, S - $56.99 Licks And Giggles Boutique S - $56.00 Hot Whiskers Pet Boutique XS, S, S/M, M - $64.00