I could not find the .wba files for these themes anywhere on my PC, if they even exist.
As far as I can tell they were just textures applied to "something" (maybe Diamond?). The good news is, if you really want them, you can still find the texture images (.tga's) via Windows Explorer in the Windowblinds skin directory. They're in the directories Aero, Aero Clay, Aero Metals, Aero Wood. You can then use them to make your own textures, for your own personal use only, which you can then apply to any skin. See the "Create effect" button at the bottom of WBConfig's Textures page.
It might take you a few tries to get it the way you want. but there you go.