guess it all depends on which one you wanted.. could try solas in christchurch direct... cheaper than going through a dealer...
AJSP are really quick with there shipping too!! probably quicker than getting something shipped from christchurch!
Ideally you are after about 0.25 mm and it should be even all the way around the wear ring. Check to see if there are bulges in the wear ring as contact with them can cause the kind of wear that you have. Either way its far too much clearance and will be causing a performace loss.