Where can I get a small, plastic, ratcheting swivel?

This is hard to describe: I'm working on a project and I need to fasten one plastic disc about 3" in diameter to a second one by a small swivel in their center so the top disc can rotate clockwise or counter-clockwise. The swivel needs to be small and ratcheted (meaning one would hear it make distinct clicks as it turns and it would keep the disc from rotating on its own). The closest thing I can think of to illustrate what I'm looking for is the kind of ratcheted swivel that some belt-clip cell phone holders have like this one: http://www.theclip.com/store/images/D/d-16373.jpg

Any idea where I could find something like that? Any idea what the correct term is for a component like that? Thanks....