What is a reasonable rate that a coach should charge for teaching rec players?

So I've been playing tennis for about 8 years. I played some amateur competitions this year, won 2 titles and 1 final and record of 26/7. I would say I'm around a 6-7 UTR by now, and I'm really passionate about teaching tennis to others, I've done it in a few occasions here and there but not so often. But, I really wanna give it a shot from now on. I have a lot of coaching material and I feel like I have good knowledge and observation, that I can help people learn the basics. I'm already working on improving my game for next year's tournaments hence I'm gonna play in a higher division. And with coaching, I wanna start advertise, giving like a 1+1 free lesson. I do not have amy certification yet, but planning to get one. I have an idea about what I want to charge, quite less obviously, but it would be good pocket money regardless.

What do you think would be a reasonable rate? :) Thanks in advance!