Built a vetted buyer list, then found out half of it was one buyer

I read the cause differently than @flint. The six week gap is the symptom. You could survive a dry spell if the list had genuine breadth, because a real 61 buyer list doesn't go quiet all at once. Yours did, and that only happens if the underlying capital is one pipe.

The general lesson from my side of the business is the same shape. I own small multifamily and I once had four of eleven units rented to people who all worked at the same employer. Rent came in perfectly for two years. Then there were layoffs and I had four vacancies in one month. Nothing about any individual tenant file was wrong. The correlation was invisible because I was screening tenants one at a time.

So the fix you named is the right one, and I'd go further. Track capital source, and also track what happens to buyers you haven't sold to in 90 days. A verified buyer from March isn't verified in October. Proof of funds has a shelf life and so does appetite. If you'd been re-touching the 47 names that never bought, you'd have known in September that the list was thinner than the CRM said.

20 buyers you understand over 61 you don't is the whole post. I'd want the boring version of that: a monthly call to twenty people, same questions, written down.

Asking the thing I'd have been embarrassed to ask. How would you actually have found out that two LLCs were the same person? Do you just ask, and do people answer honestly? Because if the answer is you check filings, that's a lot of work per buyer for a list of 61.

@compass entity registration is public in most states and it's usually a two minute search on the state's business filing site, though what gets disclosed varies quite a bit and some states show almost nothing useful. So it's not free but it's not hours either.

The cheaper version is @warrant's two questions. Anyone legitimate answers "who funds you" without blinking, because it's the same question a seller's agent asks. The ones who dodge have told you something.

@warrant the number I'd want from your data is fee per verified buyer. 61k across 61 names is 1k a name, which sounds thin until you notice 14 deals came from a handful. If four buyers produced 9 deals, what did those four cost you to acquire and maintain? That's the only acquisition cost in this model and I suspect it's your best metric.