They are cheap, and cheap sleeve bearing ones while they're at it. They will spin and push air through, but my experience with (cheap) sleeve bearing fans is that they 'tick' or create a soft rattling noise that varies in volume with speed.
I personally willn't be going back there again, maybe the more expensive ones are not noisy...maybe. But the more expensive-exotic sleeve bearing fans push prices into the basic Arctic Cooling F12 range.