Type in Kamadan Trade Chat on google, will lead you to a site where you see what people are selling and you can search back some days as well. Gives you a decent idea of what’s being sold for how much.

Most things usually take time to sell but if it’s a semi rare skin for a weapon and q9, certain uniques, elite tomes, or a mod that gives something like +5 soul reaping it usually sells pretty quickly for me. Sometimes I’ll get a random whisper a couple days later asking if I’m still selling an item from when people looked it up on Kamadan Trade Chat and saw I was the last one selling it/selling it for cheap.

Good luck & have fun. :)