Keh (https://www.keh.com/) is sort of like this, except that they function more like a second-hand shop--you sell them your gear, and they hold inventory that other people can buy, meaning you never actually interact with the eventual buyer. Because of this though, I imagine they take a larger cut than Reverb does (and certainly more than eBay).
As a buyer I've had zero problems with Keh the couple of times I've used them.