That is the case of course in this instance but still it isn't cheap enough anymore where I will just purchase off the cuff. Some now are £40 (Monster Hunter for example right now) for all the content which is a huge price increase from years gone by.
I'll take your word on the prices of game bundles since I haven't tracked that.
However I've bought book bundles every year for the past 8 years. In 2018, a full bundle was usually $15, with a suggested price of $25. Starting in 2021, the bundles were bumped up to $18, still suggested at $25 (but O'Reilly bundles cost more).
15+3 is a 20% increase, but is still below retailer's $20 threshold "impulse buy" rule of thumb.