remember nori is pressed and toasted laver, not kelp. I am unsure of it's nutritional content but no doubt it is high in K and iodine.
If you want seaweed, any seaweed, and are asking at food places, any of these might work: wakame, hijiki, kombu, etc... chinese kombu is very cheap, but the japanese stuff is very expensive. Hijiki would be the easiest to work with as you could just mix it in. wakame expands a lot when it gets wet.
for an interesting adventure, try the cookbook "washoku" by elizabeth andoh. it's worth it just for the kabocha with adzuki beans recipe. Which uses kelp, by the way.
a nori sheet is basically paper made from seaweed paste. There is not a lot in there. If you like miso soup, by the way, al you need is kombu (kelp), dried bonito flakes, and some miso. Wakame is optional.
MARYJ.........U know U'r SCHIT.........KK++........................one cook to another........