I have never bought anything on CL but used it occasionally to sell random “garage sale” type items. As a seller the problems I see are:
1. 90% of buyers are flaky/not serious. They’ll send me one email saying they are “very interested” then when I reply I never hear from them again. Pretty annoying.
2. Of the remaining 10% of buyers most seem to either want your goods dirt cheap (much less than fair value) and/or will pull a bait and switch by lowballing when I meet up to sell the item.
Personally when I sell items I always list them slightly higher than what I actually intend to get, to account for the fact that everyone tries to negotiate. So maybe that is factoring into the high prices that you see.
