Thought this may be helpful for those of you looking for an inexpensive rig. I was walking through Fry's Electronics and came across a ball and socket "helping hands". Thought "hey, that would make a great rig" and snatched 2 of them up. I took off the magnifier and the alligator clips and added a long threaded rod as an extension. I will be adding a wider/heavier base since the small one it came with tips over when the arm is extended and defeats the purpose. It's not the most reliable piece, but will work great for light-weight puppets or props. Here's a photo of a before and after. If you're in the US, you can buy it online here, but the shipping is more than the piece.
i bought a few of those too!! they are great!!
I have a few of them as well, they're indeed best used for jumping rigs and I did tests with Lego Bionicle and Stikfas figures. They work great. I'm none too sure whether they make the best armature parts unless you only use them in strategic areas where there is little weight distributed. I probably should try that.