Not sure what kind of domainer he is, but I suspect strong affiliation, possibly stakes in SAV, because that is the only way $280 would make sense at such a scale (drive traffic to another product).
So, if they buy 10000 names like this, spend $80K, sell 200-250 names at $280 for $56K to 70K, while getting about 500 000 visitors in a year, then they paid $10K to $24K for that many people or 2 cents to 5 cents, which is quite cheap, as normally more than half of it would be from the developed countries.
SAV is definitely disrupting the business model in a bad way. Another reason I am avoiding them at any cost. Normal investors need $xxxx prices for the business to be profitable.