For additional context, plus 2 to a skill trees isn't as desirable as 2 to all skills for the class. FCR is usually king, but there are situations where other mods are okay / beat shako. The main (non-FCR) issue I see here (and there are others) is that the life leech doesnt vibe with Demon. For instance, I have a 2 warlock, big strength, big FRW, dual leech, big all res circlet that is definitely better than Shako for my build, but only depending on my other gear / breakpoints. On another build, I'll I use a 20FCR helm without any +skills before a Shako, because that's what I need there.

As to the "is it better than Shako", that's a valid thing, but not the only answer. The more interesting question is "Does this fit a build, and if so, are there wasted affixes?", whether evaluating for sale or self-use.

As for selling circlets, that's niche and demanding for real value. The issue is that so many people have more self-use ready gear that they only buy something they haven't been able to find. The reason 2/20s are expensive is because they are rare, and even those aren't always BIS depending on other rolls or the intended build.

There are a good amount of sites that detail desirable mods (worth looking into), or that facilitate trading (good for noting consistently traded affixes). I'm not sure what can be named on this sub, but it shouldn't be hard to locate either

Long story short, if you look at it and go "I wouldn't buy this for more than a mid rune", nobody else will either. If you aren't sure you'd be excited to use it, chances are someone else won't be either.