You can charge money, you can have special rules outside of the scope of the GDPR... what you cannot do is make people’s personal data the price for content. Under the GDPR personal data is non negotiable.
Edit: I'm surprised that elondaits's explanation isn't at the top of my thread. It makes clear that "exchanging your data as payment for 'free' services" is the target of GDPR and seems to me that's the only sensible explanation. Is someone willing to refute their explanation?
Yeah, I guess it could be thought of like laws against prostitution... you can give your data away for free, but you can't give it in return for something.
Price for a service isn't guided by how expensive the service is to offer, but by what the market will pay.
In this case, however, I was using it as an example of setting a price you don't expect to be paid... you want everyone to pay with their data, but you are required by law to offer an alternative payment form... so you set the price for the alternative to so high no one pays it.