Can't find where to buy HDD sleds for Versa N21 Case.

[zc630 2]

I have two HDD's installed to my Versa N21 case, and have a third HDD I want to install; however, the case only came with two sleds, and I can't find where to buy a third sled for this case anywhere. Any help?

 

Pictures of needed sled: http://imgur.com/7WEwgUx

                                       http://imgur.com/efBxhrz

                                        http://imgur.com/2akldVc