CDNN has the 10-rd mags in stock.
http://www.cdnninvestments.com/bdm9mm10blun.html
I have one & love the feel in my hand and the way it shoots, but it is completely unreliable. Everytime I take it to the range, I almost always have at least 1 FTF or FTE.
Every now and then I keep an eye on Gunbroker to see what they are selling for, very rarely do they sell for over $400.