How much would you charge to re-develop and maintain 9 websites for the same customer?

I talked with a possible client who has eight current websites, all of which have SEO and some security issues. He also wants another website pretty soon.
I wanted to offer him redevelopment of the websites on WP and Elementor, maintenance and SEO for him, and maybe content creation. Someone told me I undercharge for my services. In general, I take $330 for a simple website creation, regular maintenance, and simple content creation. I include SEO in my websites and simple content creation or assistance.
Is this way too low or what do you guys charge for that? Emails have a 1 GB space limit.