The GDPR says that if you use consent as the legal basis for processing data, such consent must be free. This means that there cannot be consequences if you give or not give the consent. If there are, then the consent is not free anymore. Paying money for a service is absolutely legal, obviously, what probably is not legal is extracting your consent by offering you a discount (which is the flipside of “pay to avoid tracking”).

I just wanted to specify a bit, not that you said anything incorrect.