Don’t know about Facebook Groups, but if you’re serious about selling it, PM me with last 3 months of analytics, payment information of last 3 months as well.
Alternatively, You can give a shot to Flippa or Empire Flippers.
Quite Right, The only solution to this is take like 10% advance refundable payment from users who are willing to know the URL before buying. It’ll reduce the ratio of time wasters and keyword stealers like 70-75% . Even ifs its refundable.