They are gorgeous aren't they. I think they are mine in classifieds unless there are more!
They are custom made by Tami at Dunk'n'Fluff, she very seldom lists wrap slots but if she has an 'anything goes' slot you can use that to get some. You can get standard ones using any of the fabric in her gallery.
The ones I have are made from Gymboree Blankets, you source & buy the blanket yourself and Tami makes them into wraps, so they are a bit more expensive than your standard wraps.
Hope that helps!
ETA: She has 2 Anything goes slots at the moment http://hyenacart.com/Dunk-n-Fluff/
Also, check you do need a large as Dunk n Fluff sizing is more generous than most!
Rufus is 22lb and has loads of room in his Medium.