Well I really dont know too much about these, but I did a search on Amazon and this is everything that came up for Karaoke Revolution.
http://www.amazon.com/exec/obidos/search-handle-url/index=videogames&field-keywords=karaoke%252520revolution&field-browse=468642&search-type=ss&bq=1&store-name=videogames/ref=xs_ap_l_xgl63/103-4071414-7104640
