Heaps of sales Comixology atm
60% off Dynamite (with code DYNAMITE16) - https://www.comixology.com/Dynamite-Linewide-Sale/page/13253
50% off Dark Horse (I just bought all the Groo books) - https://www.comixology.com/Dark-Horse-Black-Friday-Cyber-Mon…
BOGOF DC (doesn't include Rebirth issues from issue #2 on) - https://www.comixology.com/DC-Buy-One-Get-One-Sale/page/1325…
Marvel Collections Sale - Save up to 80% off - https://www.comixology.com/Marvel-Collections-Sale/page/1320…
Star Wars Collections Sale - Save up to 75% - https://www.comixology.com/Star-Wars-Collections-Sale/page/1…
End dates vary but most seem to end at about 2:30pm 29/11
NOTE: These are DIGITAL COMICS and you wont receive a physical copy.
Sales may also be direct with publishers or on other services like Google Play. Personally I like Comixology as everything is in one app.