I'd recommend sticking with the dried macro-algae sold for aquarium fish, such as the excellent Seaweed Selects from Ocean Nutrition. You MIGHT be able to find a similar product at an oriental grocery store but many of these are either cooked or have added seasonings. It's not worth the hassle or risk to potentially save a few dollars. Also, it doesn't pay to buy a large batch of these products because they go bad in a few months.