Sprue Brothers is a great source, but they have lost many of my business to their poor search engine. Obscure subjects and after market parts are hard to find. The thing is that most of the times I know they do carry them, but I can't find 'em.
Scale Hobbyist is a great source too and often with better prices than SB's. If the item is in stock, it is in Green. If not, it appears as back ordered in Red. Available means that they might get it in 3-5 days in Yellow.