I have my annual calendars printed from saal digital since ~10 years. In October and November they have special offers up to 60 % off their usual price, which I always try to manage. The quality is very good, and the value for money is excellent IMO.
I prepare the calendars in darktable and scribus with a calendar strip generated with LaTeX. Part of my process is documented here: PlayRaw Calendar 2018 (A Calendar Making Tutorial using FLOSS Software) – Part 1 & 2 - #3 by paperdigits.