Where to japanese buy seaweed salad to eat at home?

I am a big fan of the japanese seaweed salad you get from most sushi places around town, but it’s pretty expensive to buy in the small takeaway containers. I am wondering if it can be obtained in larger quantities.

Yes, go to an asian grocer, I get it…but every time a buy a seaweed that seems like the right thing…it’s not…tastes awful and nothing like the salads you buy. Maybe it’s the dressing?

Any tips appreciated.