Yeah... I did that.
I used two cheap clearance Bossks from the PotF2 green card blowouts to craft my two custom Saurin. One, I did just what you said Scott, I used a Ponda Baba body and painted him (black pants, ugly green/yellow jacket like in the picture.
The second, to be a bit different, I used a Ep1 Rune Haako for the body and painted up the robes. This gave the second one a different look, with a bit of a difference in height and head position.
BUT, I'd still like an official Hasbro version though.
I really should get off my lazy ass and finaly take some snap shots of my custom figures now that I have a digital Camera... maybe I'll do that tonight with a feature on my Cantina Customs?