I tried to get some stir bars from Livingstone, with no luck. They wouldn't let me register an account, with their reply of-
"Hi, We were very sorry to inform you that right now we cannot accept your registration with us because we need to follow instructions given to us. We were very particular about the companies to approve and at the same time what are they doing. Kind Regards, Sheila Bolivar"
Just thought i'd pass on the news. Back to ebay it is!
Try Wiltronics, although it looks like they only have the stir bars with pivot rings.
Got a pack of 4, 8mm*30mm PFTE coated stirbars from "proscitech" for around $13 i think!!!