There was an msstyle theme converter that could import xp themes to .wba . Not perfect but produces sometimes really good results.
You may also look at gnome-look.org and clone some themes from there to gtk2 to .wba for your own personal use. ( second not exactly a joke, but also not a helpful answer for you i think).
You`ll have to search for similar plattforms. And the closest ones i do know are the one from msstyles XP and the linux GTK2 Pixbuf engine or gtk3 ( however you do sometimes need to capture each element and remake the complete theme file structure.). However there are itself highly different from Stardock window blinds. You do need to do a lot with your own mice and keyboard to make it.
Deviantart has only few and you might find two or three other sides providinbg .wba ( sometimes outdated). The best site is wincustomize.org for window blinds skins.
regards bluedxca93