Around here, in the Star Wars Customs section, we mostly make our own stuff, and then offer it to others on the board. We ask for help or collaboration on things, but I don't think I've seen a single "commission," well,
commissioned in here to date (since the Star Wars Customs subsection was made distinct from the Star Wars Section and the Customs section, at least. Please someone correct me on this if I'm wrong...)
To me, the idea of commissions seems very impersonal. In a commission, it implies that both the artist and commissioner are acting in their own self-interest (the commissioner for the finished piece, and the artist/customizer for the money). In this subsection, I think we are less about the money, and more about the joy of customizing and helping each other out.
I dislike the idea of people only customizing something because they're being paid for it, or that a commissioner becomes the "boss" of the customizer commissioned. It just doesn't sound very nice to me.
Just my two cents on the subject... Don't mean to seem snooty or opinionated or anything, I apologize if I come across that way...
Anyway, instead of trying to commission people to do stuff for you, you could always just ask around and see what's already here (like the Nikto head, for example.)
Hope you find what you're looking for.