A lot of higher end N routers are dual-band; they work on both the 2.4 GHz and 5 Ghz bands. It would be silly to have a router that only worked with 5 Ghz, since many laptops and almost all cell phones only work with 2.4 Ghz. Routers that work with 5 GHz should be relatively easy to find - just make sure that you search for "dual band" instead of 5 Ghz.