[thiht]

The ICANN states that you must provide a way to directly contact a domain's owner. If I'm correct, the contact info must be freely available in the whole, whether it's an email address, an obfuscated email address, or a contact form on the website of the registrar.

Charging for this is really shady, but not contacting the domain owner when requested is a registrar agreement violation.

Note that it's also the responsibility of the registrar to ensure that contact information of their registrants are correct.