Grok charges $20/month for basic access, $50/month for premium features, with a...

https://wiki-global.win/index.php/How_Much_Are_the_$25_Grok_API_Trial_Credits_Worth_in_Testing%3F

Grok charges $20/month for basic access, $50/month for premium features, with a cap of about 10 prompts every 2 hours to manage usage. There’s no free trial, so you’ll want to be sure before subscribing