This is the website that offers this kind of service I'm surprised that it's from India, where they are very strict from Cryptocurrency believers and holders, there is no mention of the cost, but I figure out it's going to cost a lot of money, looks good they offer many services related to Cryptocurrency
https://www.antiersolutions.com/cryptocurrency-exchange-development-company/Yes, even I was surprised to see that these guys offer so many services related to crypto-development.
I personally do not think they charge a lot for their services because companies in India usually cost relatively less for their development solutions. This is one of the reasons why international companies outsource their development projects to Indian companies.