I would not reccomend buying the ones from ebay as i recently tried fitting some and half broke while doing it I believe that the plastic on these so called new ones has gone brittle over time and i tried heating them up,but to no avail,as i regularly find bits of them under my car in the garage
I am going to make some stainless ones soon as i reckon that they will be better than alloy,with a stainless screw to fix to body and a pop rivet to the plastic.

regards mark