Edit: Whoops, seems this is limited to PSN accounts in the Americas. So there's a small hurdle to jump if you're elsewhere (AFAIK: make an account in the area and register your PS4 to it), and it might just sidestep the PS+ complication.
Humble Indie PlayStation Bundle 2019. As usual for console bundles, the average price went up from the start, so the Beat the Average tier is at $9.20 now.
$1:
Grim Fandango
Bard's Tale
InnerSpace
BTA ($9.20+):
Broken Age
Layers of Fear
Talos Principle
Wasteland 2
$15:
Killing Floor 2
Shadow Warrior 2
You get a single key for each tier.
Remember, Sony's digital storefront is stupid, so if you "own" a title from PS+, you can't actually buy a digital copy (ie, upgrade from a temporary to a "permanent" license) until your PS+ subscription lapses. Grim Fandango, Broken Age, and Killing Floor 2 have all been free with PS+. If you own one and redeem a tier, you'll essentially be throwing away that duplicate game in that you won't get a permanent copy.
I got in early just for the Talos Principle (which should be the Deluxe Edition with the Road to Gehenna DLC, as that's the only version Sony's sold).
The cheapest it's been in the last two years is $10. (Edit 2: Yup, it's the Deluxe Edition.)