There are a few costs associated with supporting a new coin for exchange. You need to maintain a node, keep up to date software version and familiarize yourself with the protocol to make transactions. So to charge a listing fee should be somewhat commensurate to what is previously mentioned. I know of one exchange which may be willing to list Grin without charging exorbitant listing fees which is FreiExchange although they seem to focus more on the older generation of cryptocurrencies. After that there are not too many exchanges that would provide anything different from the services already provided by Gate and Ogre. A Kraken listing could integrate Grin with some more liquidity but that seems increasingly unlikely as time goes on.