I had seen photos of this mouthpiece but hadn’t been able to find a source until recently. My minimalist approach in playing my Suzukis has been to use the fitting from a blow tube, until this morning, that is, when my latest order from Japan arrived.
It sells through Yahoo Japan for about $7 U.S. My purchase was through Buyee. I ordered two, hoping to save on shipping. Total cost with fees and shipping, however, came to about $20 each, $40 total. There must be a better way, but I love this smooth little mouthpiece, which sits very comfortably between the lips.