I suspect they've counted "converted" as "entered an email address" or "signed up". That would then explain the long-term value: lots of value from a fraction of customers, and zero value from the rest.
Alternatively, given prices like those they put on the big price tag on the "Problems / Solutions" slide ($150), $3 sounds about right for the affiliate/kickback benefit they'd get from the retailer.
Ah, that's the "AppSumo" part of it, then. I assumed that since they had a "Buyer" in the core staff that it was more like Woot! where they'd have inventory themselves, but it looks like you are right.
I think Woot has a buyer too. Buyer, in retail, means more than the person who pays, it means the person who finds the products, makes sure they're up to the standards of their brand, looks for the best deals on the good, sources the deals, generates the PO, etc.
Alternatively, given prices like those they put on the big price tag on the "Problems / Solutions" slide ($150), $3 sounds about right for the affiliate/kickback benefit they'd get from the retailer.