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

I guess it depends on region, but in mine Lost Ruins of Anark, Terraforming Mars, and Scythe were pretty cheap. Also saw Patchwork on a decent discount.

I usually check BGG hot deals. You can subscribe and get notifications when others post deals.

In spain I saw a few good ones.

Top of the list is castles of Burgundy for 30 euros Others worth mentioning was Pandemic and Pandemic legacy, Agricola and 7 wonders architects