Yes, you got it right – you can shop for free in this supermarket bordershop Priss in Süderlügum at the Danish-German border at Sæd in Jutland.
Unfortunately this was a one time onlys event on the opening day, and the shopping was limited to DKK 2.000 or app. USD/EUR 300. And only for the first 100 customers. Anyway, people came from alle over Denmark, already the day before the opening. Happy shopping!