Thread:Project:Support desk/Selling Media wiki skins?

Hi, I'm a web developer and I was just wondering if it is possible to sell Media Wiki Skins?

And if so, is just supplying my own code in Monobook legal (I.E my own HTML and CSS)? Monobook.php does not specify a license, unless there is a way to do a skin from scratch so that I may attach my own license.

Sorry if this was not the clearest post.