I might have a pile of those in the house, bought in error. If it's the right ones you can have 'em for nowt. I'm in Marrickville.
EDIT - looked at the ones referenced in Doc's post, not the same as what i've got
Also give these guys a call (also in Marrickville, next to Marrickville Metro)
http://www.niceproducts.com.au/
they seem to stock pretty much everything and they are the wholesalers who supply Repco amongst others (Repco referred me to them when they said they had to order them in and i said i needed them now, so they just told me where to go direct)
Page 17 of the catalogue perhaps?? first item on the page
http://www.niceproducts.com.au/catalogu ... /wheel.php
Or page 25, 3rd one down, think those are the only 3/8 ones they have