Schumacher sell them direct :
http://www.racing-cars.com/sp/catego...d_Inserts.html
Although they are currently showing out of stock on the fronts.
Apex Models are also listing them, the website doesnt mention whether they are in stock or not though.
http://www.apexmodels.com/gbu0-prodshow/U3765.html
I cant comment on whether the Rulux wheels will fit the Cougar as I dont know, but what I can tell you is I have just bought them for my B44.1 and they look the business....
http://www.jespares.com/nitro-models?page=shop.browse
Hope this helps...