Thumb Score: +1

Amazon has Tetra Whisper EX Carbon Filter [Large, 4-Pack] priced at $ 9.49.
Cheapest I’ve seen in a while.

FYI Large fits filter EX30, EX45, and EX70

It’s listed as an Add-on item (can always order with Alexa for free ship):

https://www.amazon.com/Tetra-Whis…B001KN959I