There are a wide variety of router bits available today. The number of bits is limited only by the imagination of the companies that make them. You should be able to find them at your local hardware stores or by mail through a catalog. They are made all around the world - from the United States, to Israel, and the Pacific Rim. The vast majority of bits on the market today are carbide tipped.
Carbide is an extremely hard material.
This is why most bits are carbide tipped and not made from solid carbide. They are still available from a number of hardware stores and catalogs. HSS bits are best suited for occasional work. A HSS bit is considerably less expensive than a comparable carbide bit. HSS bits tend to dull relatively quickly and need to be re-sharpened to keep from burning the wood's surface.