I heard that fees for listing altcoin is too expensive even in small exchange site.
Take a look at this article here
The Cost to Get Listed on a Crypto ExchangeAccording to the article the listing fee is around $6,000-$30,000 for small exchange and $60,000-$300,000 for medium size exchange and for big exchanges the fees is too expensive.
I don't know if this is accurate but I believe that there are some exchanges with lesser fee.
That absurd when the market is sleeping arent they also get fee from trader. If you total all the moeny they collect in one alt then they can really a big sum in a year with it specially when the alt are active at trading.