How can I force customers to login to see prices in my ecommerce design?

No problem

I see you have different product pages. Try this at the end, instead of what you can find in the article, to hide those different elements:

{% comment %} END CUSTOMER CONDITIONAL {% endcomment %} {% else %} Please login to see the price

form[action=“/cart/add”], .product__block__quantity { display: none !important; }

{% endif %}