Yes, you can do this without spending a lot on a website builder.
Since you already have your domains and your ClickBank affiliate links, you have the basic pieces you need. You don't need an e-commerce system for this because you're not selling the products yourself. Your website can provide useful information about the products and then send visitors to the ClickBank offer using your affiliate link.
UltimateWB would be a good option for you, for ease of use, features, and affordable pricing.
It's much easier to build and customize with UltimateWB than dealing with WordPress, themes, plugins, and all the different pieces that can get confusing.
You could use UltimateWB Promo Unlimited, which is currently a one-time $34 purchase and gives you unlimited pages. You can also get UltimateWB hosting for under $5/month, so you're not taking on another expensive yearly website-builder subscription.
And if you run into something you don't understand, we provide free technical support.
You don't have to know programming to build the sites. It a WYSIWYG - what you see is what you get - page editor system.
I'd start with just one of your three websites. Get that one set up and working properly first, then you can use it as a template/starting point for the other two.
For example, your first site could have:
A home page explaining the niche
A page for each of your four initial products
Useful articles related to the niche
Your ClickBank affiliate links on the appropriate pages
An About page
A Contact page
Simple navigation so visitors can easily find what they're looking for
I would also avoid making the site nothing but affiliate links. Give people useful information about the niche and the products so the site has something of value to visitors.
If you already have content from your WordPress setup, you can copy and paste that into UltimateWB. And if Gemini has already made a mess of the WordPress sites, you also will probably find it easier to start fresh rather than trying to untangle everything.
If you tell me what your first niche is and what the four ClickBank products are, I can give you some specific ideas for how I'd structure the first site and how you could build it in UltimateWB. I'm online now on Live Chat if you would like to chat there.