Look in the furnture parts aisle at Bunnings (wooden pre-made legs, feet, coasters etc) - they have knobs with either a bolt pre-installed, or you can just purchase the knobs.
I bought 6 at Bunnings Fyshwick last week for $2.96 each.
Thanks all, Bunnings was a fail for a match, Ill look at the other ideas but if I cant find a match Ill cast some in resin, it would be a lot easier to buy them