Are the powerline adaptors actually good? Are the cheaper ones good, or is it only worth it when you start spending a lot? I saw this on amazon and almost bought it

Which powerline do you have? Do you think this cheap one would cut it, or would I need a better one like this more expensive one

Pretty much. You plug into an outlet, ethernet into it, and elsewhere in the house you plug another one in, and ethernet out of it. It's not as good as a straight ethernet cable, but it's better than wifi. https://smile.amazon.com/gp/product/B010Q29KRK/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

This is the one I'm using. I've got a Roku and Steamlink in the bedroom running through it. But my wireless router is only 1 room away, so I could be fine on that I suppose. Just had it from another house where the router was on a different floor.