This law is an old one and has been in effect forever (offline and online). I'm certain there is a lot of legal practice and precedence on what can be expected

This law is an old one and has been in effect forever (offline and online). I'm certain there is a lot of legal practice and precedence on what can be expected of a "reasonable" company. Courts are usually quite pragmatic in their rulings (otherwise no law would ever work) The Goal is to prevent misleading advertising and tricking of the customer by showing them a different price. A typical costumer won't use a VPN etc, so if you can demonstrate that you had a sufficient amount of evidence no court will punish you for it. E.g.: German IP, German browser, a German credit card and a German shipping address are probably sufficient. Edit: it used to be that you have to go to great lengths to ensure that no consumer can shop in your B2B shop (like verifying their business license, making sure the customer isn't lying etc). In recent years the federal high court ruled on several occasions that this is not necessary and a simple disclaimer and a checkbox is enough in most cases (IANAL).