PSA there’s a big sale on the eshop until April 27. Quite a few first-party titles with a 33% discount and others with bigger discounts. I picked up Portal 1 & 2 for about £3, it really is good.

I also discovered https://www.dekudeals.com/ recently - it tracks prices over time so you can see how good the current discount is and physical/digital from different retailers.