Subscription is a common model for things like this, particularly because it’s so easy for people to make direct approaches to the vendor, cutting out the middleman to avoid the commission/fees
I like the way Flippa does it: https://flippa.com/
Show what's listed, show basic financials and an asking price. Only after a buyer sees something interesting are they asked to jump through hoops to create an account, etc.
Looking at the listings, they would be really hard to de-anonymize.