Santa was kind enough to bring my daughter Karaoke Revolution, and we've been having a ball with it. But, the microphone looks like it belongs to a 70's cassette recorder. (It's the same style as the Mario Party mics, just black.)
I saw that Konami made a pretty nice looking mic for the PS2, but after Googling the crap out of it I couldn't come up with anything else for the Gamecube.
PS2: turned 10 years old yesterday. See: list of developer's favorite games. It was supposed to last 10 years, and they were still putting on new games this week. (Not many, but not many for PSP...) $$$: