The numbers I wrote down
Steam, app 3247750, English store: US$14.99 list, US$7.49 on the page that day. SteamDB is the chart I trust for whether that discount is the historical low. The store's sale end and SteamDB's end can disagree by a day because of UTC.
PlayStation US: US$14.99 standard, US$19.99 Deluxe, US$6.99 Supporter Pack. Japan: ¥1,760, ¥2,420, and ¥880. Steam Japan showed ¥1,700, half price ¥850 during the same window. A Japanese blog's 値上げ talk is about a price change rumor, not a second list price I could verify on the US page.
Why I skip third-party keys
The search demand around cd keys is real. The official price is already low, and a grey-market key can be revoked. I would rather pay Steam or PlayStation and keep the library entry.
If the sale ends, the list price is still US$14.99 until the store says otherwise. I will not invent a future increase.