For the home cook, its usually a better strategy to spend money up front on quality, but ignore specialized tools, than try to cheap out. Alton Brown's advice about unitaskers is terrible, except for the first time you start cooking at home and don't know what you need.
Someone could spend days looking for the specific slow cooker you found and maybe your onions from it are good. The idea of saving 50 dollars by buying an unglazed piece of quarry from Lowe's for 5 bucks instead of a proper pizza stone is a popular myth. Anyone who has actually tried it, has probably wasted hours on the internet looking for it and when the idea came out was most likely wasting tons of gas going to multiple Lowe's.
Maybe you got lucky and your 5 dollar slow cooker really makes good caramelized onions. But my experience trying recipes over the years, there are a few good sources of free recipes from a few places on the internet, and nearly everyone, without a team of testers backing them, is at best mediocre and usually sucks. Published recipes in a proper cookbook tend to be of higher quality, but its not always a guarantee. You get lucky every once in a while and find a hidden gem, but its almost never worth the effort to try non-established recipes as a beginner cook that can't read a recipe and immediately find red flags.
I guess this is just a long winded way of saying that maybe your cheaply made onions are good, but after being a home cook for so long I think it is more likely the caramelized onions in my Le Creuset are going to be better. I don't think you're lying for clicks like many recipe blogs out there, but you might just not realize what you could be eating.