Humble 13th Age Bundle is a pretty good price for $25 and includes a lot of short adventures and at least one big campaign. Definite buy.

PEL-13A-01 13th Age (2013) - core rules
PEL-13A-02 13th Age Bestiary (2014)
PEL-13A-04 13 True Ways (2014)
PEL-13A-05 Shadows of Eldolan (2014)
PEL-13A-06 Book of Loot (2014)
PEL-13A-07 Eyes of the Stone Thief (2015)
PEL-13A-08 13th Age Soundtrack (2015)
PEL-13A-10 13th Age Gamemaster Screen and Resource Book (2015)
PEL-13A-14 13th Age Bestiary 2 (2017)
PEL-13A-16 Book of Demons (2018)
PEL-13A-17 Book of Ages (2018)
PEL-13A-18 Loot Harder: A Book of Treasures (2018)
PEL-13A-23 Crown of Axis (2021)

13th Age Quick Start Rules (2021)

You can buy both 13th Age Monthly collections for $50, the below is a subset of articles and each article is $3.

Adventures! (5 articles from 13th Age Monthly)
Characters! (7 articles from 13th Age Monthly)
Monsters! (9 articles from 13th Age Monthly)
Treasure! (3 articles from 13th Age Monthly)

Each of the below is about 45 pages with three short adventures and battle maps.

PEL-13A-11(A-C) The Archmage: Maps and Awesome Adventures (2016)
PEL-13A-11(D-F) The High Druid: Maps and Awesome Adventures (2016)
PEL-13A-11(G-I) Orc Lord: Maps and Awesome Adventures (2016)

Crusader: Maps and Awesome Adventures (2017)
Diabolist: Maps and Awesome Adventures (2017)
The Dwarf King: Maps and Awesome Adventures (2016)
The Elf Queen: Maps and Awesome Adventures (2016)
The Emperor: Maps and Awesome Adventures (2016)
Great Gold Wyrm: Maps and Awesome Adventures (2017)
The Lich King: Maps and Awesome Adventures (2016)
Priestess: Maps and Awesome Adventures (2017)
Prince of Shadows: Maps and Awesome Adventures (2016)
The Three: Maps and Awesome Adventures (2016)

Dragon Empire Map