I don't know if there's someone here who owned a crypto exchange listed on CMC that doesn't have a volume. The best thing you can do is manually check the
CMC ranking exchanges and contact them that you want to buy their exchange. I saw, there are 6 exchange platforms that have no volume within 24 hours and it seems abandoned by the owner or not being active.
I tend to agree with the suggestion above, why you're interested in buying exchange platforms that don't have volume, it likely risky on your part because that exchange might have a bad reputation or turn out into an exit scam. Instead, alternatively suggestion, you can buy a crypto exchange domain name and build your own crypto exchange. Here is the list of
300+ cryptocurrency exchange domain names for sale including the price. This will make sure that you're not most likely wasting your money.
Otherwise, you can have your decision at all times because that is your money. Think twice before you will act.