Pricing
There are two things to price here: getting listed, and sponsoring the audience that reads the list. They're unrelated, and the first can never buy the second a better position.
Listing in the directory
$0. Always free. Cannot be bought, upgraded, or bought out of.
Every listing — free app or paid app — gets the same hand-verified treatment: price checked at the source, claims checked against the developer's own site or the Mac App Store, "unknown" used instead of a guess. See the editorial policy or submit an app.
Sponsorship
Not rate-carded yet — pricing an unmeasured audience would be guessing, and this site doesn't guess at numbers it publishes. What's for sale: a labelled placement in the weekly digest, a sponsor block under a category page, or a launch announcement. What's never for sale, at any price: ranking position, review verdicts, listing inclusion, or removal of an "unknown price" flag — see the full advertising policy for exactly how that's enforced.