You did the math right, my ebook is $29.99.
Why are you surprised that people invest their money into developing a new skill and improving their websites?
They can buy any digital product on the web, but if they choose a particular creator, there must be something they want to learn particularly from him/her.
Furthermore, I've been in the SEO industry since 2015 and worked with many clients. Besides, I've been selling products for 3 years. So, I don't think I fall into the category of a "newbie seller."
Your comment wasn't necessary if it's all about judgement.