Show a field to logged-in user in Drupal 8 views
If you want to hide the price field globally to anonymous users, consider using something like field permissions.

https://www.drupal.org/project/field_permissions

This could potentially hide the price in any context it is displayed.

If you need to use twig, other solutions include overriding the templates for the view(s) and/or the field itself. 

I would recommend addressing this kind of override from a code side, as it could potentially reveal sensitive information based on the front-end.