I had found the original, working switches on ebay back in 2006, bought about a hundred of them to go out with the radios we were making at the time. Earlier this year when I started working on the super-detailed Sonix radio I could not source them anymore. There are some similar ones online but they aren't exact.
As for the two smaller knobs, you can find some at Radio shack, but I think they're too tall. When I molded them up and made casts, I only filled the mold half-way.