Questions about ways to earn extra money

I am a MEI (A way to create a small company, with just one employee, in Brazil, and have lower taxes) today

I will start working with web test automation (which in my opinion does not prevent me from continuing to be a MEI, but let's not "tempt fate", right? Because in Brazil, when you work in development, you need to migrate to ME, which generates more taxes and cost, etc. Brazil sucks)

And then, when I become a ME, my expenses will increase from 80 to almost 1000 (Brazilian real), with an accountant and other fees that I found out about.

Since this contract will be a PJ (How to be hired as a company in Brazil), I see myself in the possibility of making some extra money on the side, and creating websites and systems comes to mind.

I have great experience with landing pages (personal projects) and complete PHP "crud" systems, such as a call management system that the company that hires me uses to record which system had a problem or which peripheral, which technician worked, how he resolved it and when, at which station, and generates reports about it.

My question is:

I want to start doing these extras. At first, the landing pages, hosting on my Hostgator, with the person paying for the registration.

I would like to know what the average cost is for those who are starting out with this type of service (landing page for psychologists, doctors, etc.)

Or how to price this... And if you have any other suggestions on how to make extra money to cover this extra expense for the ME.