Thank you for the Eric Shanower and Emperor Joker recommendations. Emperor Joker looks interesting, but it'll have to wait, as I purchased several books from the Fantagraphics sale. I picked up Litte Adventures in Oz, though. (And thanks to elaysee for mentioning that Kickstarter campaign.)
This link makes it easier to browse the IDW All-Ages Sale:
https://www.comixology.com/IDW-All-Ages-Sale/page/10257
I am surprised to see that Jeff Brown writes for children. All I've read by him is about his sex life and failed relationships. I'll check out his series later on.
Ends 4/29.
From Vertigo a sale on 17 TPBs or graphic novels:
https://www.comixology.com/Vertigo-C...ale/page/10274. The random weird number chosen this time is 53: "Up to 53% off". Maybe it's a subtle reference to that upcoming Rebirth event. They are moving beyond 52.

All collections are $6.99/€5.99.
American Vampire Vol 7
Mad Max: Fury Road
FBP: Federal Bureau of Psychics Vol. 1-3
Coffin Hill Vol 1-2
Effigy: Idle Worship
Suiciders
Wolf Moon
The Names
Bodies
Hunterkind Vol 1-3 (this is the whole series)
Get Jiro!
Fable: The Wolf Among Us Vol 1
Ends 4/11
From Boom a sale on Do Android Dream of Electric Sheep?:
https://www.comixology.com/Do-Androi...ale/page/10283
1 bundle, 9 collections, and 24 issues (can't check right now, but I think the first omnibus was offered in a recent Boom! bundle).
Ends 4/8.
From Les Humanoïdes Associés a sale on Moebius works:
https://www.comixology.com/comics-sa...d=10746&lang=1
It's in French, but it's Moebius, so I thought it worth mentioning. (Select "All Languages" if you don't see anything when following that link).
Unknown duration.