I've been wanting to try mutton-based recipes, but all I could find in mainstream supermarkets was lamb meat (expensive, and perhaps doesn't have the strong taste of full-grown sheep that is sometimes desired).
My guess would be to look into ethnic grocery stores. So far, I've been used to the fact that I can't find such meat in Chinese stores. How about Middle Eastern ones?
Also, I've always had the feeling that mutton meat was substantially cheaper than lamb meat. But b/c I can't seem to find it anywhere - is that true, and does the general public just hate the taste of mutton? :P