Board Game Oracle has a prime day page that makes it easier to browse through it and lets you filter further by BGG rank and other criteria.
Some small games that stand out to me:
- Jekyll vs Hyde $11.99 excellent 2P-only trick taking game
- Silver & Gold $6.49 fun flip & write by PWH
- Bruxelles 1897 $13.99 (not to be confused with 1893, this is a smaller card game)
- Pandemic: Fall of Rome $19.99 is my favorite Pandemic (along with Pandemic: The Cure)
- Horizons of Spirit Island $14.99 seems like a steal
- Glow* $23.49 is a cool drafting and dice placement game with neat art
- Coatl $20.99 is a set collection and drafting game with fun components
- Spicy $10.49 is a bluffing game that works at all player counts. Kinda like Liar's Dice but with cards