I would like to explore building a small device that can sample and display 2 or 3 frequencies. The high range (maybe 30MHz) would exceed the AVR's frequency. 0.1MHz accuracy would be great but I could settle for 1MHz resolution and the refresh rate doesn't need to be fast, 10 seconds would be fine. Is there a not too expensive circuit, component, or technique that can be implemented to do this? It's just a hobby project and I think it would be great to have a small display of rough measurements that can be attached directly to it.