You dont need to find the exact part you need listed. There are various listing on Ebay who will list a whole car, often at 99p (for which you would only get one wheel nut) You contact them for a quote on the part you actually want.
There are also on-line agents where you tell them what you want, and various scrap yards will send you offers by Email. .
A problem with scrap yards is if its a part they wouldnt normally bother removing before it goes in the crusher ,their quote may factor in labour costs for removing it specially for you. Also if removal of a small part makes a larger part unsaleable because its now incomplete, the quote may be the same as they would charge for the whole item. But may save on postage.