I buy and sell on mercari. It depends on what you’re looking for..oddities and electronics, tools, old rare books are all good buys in my experience. Jewelry was a terrible experience. Just look at their ratings and check Etsy first (for jewelry at least). If you join more groups on fb around you and widen your search radius + add shipped items, Usually some good buys pop up. I’ve sold and shipped stuff on there near and far and it’s always been a seamless experience (thus far at least). I agree about some pricing for sure-most people don’t know how to price or care to research how much their junk is worth.