From my own and @kigerneko experience Atey Ghailan offers a great "mentorship". It's a bit different though. He gives assignments each month and you hand homework in. He then corrects it in a live stream. The assignments are things you'd have to do in a game studio. He only has a very small group of students/slots on Patreon so be quick and regularly check if there are open slots. It's not that expensive either.
I don't really have a dream of working in the game industry or a fave artist BUT I do think it's very personal. Depending on your current skill and your goal you can spend as much as you like if that brings you closer to your dream job! There is no such thing as spending too much money if that one person can bring you closer to your dream job which would mean it's good value for your money.
I do think mentorships work in a different way than tutorials. With a mentorship you have a mentor correcting you in many aspects. With tutorials it's often specific skills that you train and no one's there to correct you or to give feedback.
In my opinion a mentorship teaches more because of feedback that you get and offers a wide range of developement. You also learn how to receive feedback which artists that haven't gone to art school lack a lot.
For example Im going to an art school. We dont learn character design etc but they break you completely until you can receive feedback the right way which keeps you from having a tunnel vision. A mentor would guide you in a different but similar way.
In a mentor I'd look for honesty, skills, open mind, knowledge and experience in the field.
I hope my answer is a bit helpful.