Hi Ruth. I love your Japan posts so much. Makes me proud to be Japanese. Thank you, for fancying my culture and food! This could be a good option: http://shop.mitsuwa.com/eng/egoods/edetail.php?pid=3663 What my parents did in the 80s and 90s, when access to Japanese foods and ingredients were very limited, was, befriend sushi chefs who purchased extra stock for our family. Perhaps that route would be a good option as you have such great relationships with so many great chefs in NY and Manhattan.