Hi
What is cheap and free exchanges to list a token ERC-20?
You can start to take a look at some small exchange site like hotbit or something else. I don't know how much fees that will be charged for the developers but i guess you can also start with uniswap too as it's a free listing exchange site. Someone suggested you a forkdelta to list your token but it doesn't have a lot of demand. That means there's no a lot of users are using it right now.
It's quite difficult to pick the best one on the low tier exchange site.