Although I really only converted the Envision theme for my own purposes just to see what was involved and to see how it came out, I have had a request from someone who wanted to use it.
So I have made a version available for free download here.
I cannot answer any technical queries about modifying the theme (basically because my CSS templating skills leave a lot to be desired) and I will be the first to admit that the conversion is not perfect (it has some problems displaying a few of the lists in the Admin menu - they sometimes overlap the right hand column).
That said please feel free to download and use it.
I would also recommend that the theme be installed in your
/sites/all/themes directory