While most of these resources could be still valuable, to avoid buyer's remorse, pay attention to the publishing dates, as some of them are very dated:
2022 - $18.95 - Build a Weather Station with Elixir and Nerves
2022 - $18.95 - Build a Binary Clock with Elixir and Nerves
2022 - $15.00 - Programmer Passport: OTP
2022 - $15.00 - Programmer Passport: Elixir
2021 - $27.95 - Testing Elixir
2021 - $26.95 - Concurrent Data Processing in Elixir
2021 - $22.95 - Genetic Algorithms in Elixir
2020 - $27.95 - Real-Time Phoenix
2019 - $26.95 - Programming Ecto
2019 - $28.95 - Programming Phoenix 1.4 (Current version is 1.6)
2019 - $26.95 - Property-Based Testing with PropEr, Erlang, and Elixir
2019 - $24.95 - Designing Elixir Systems with OTP
2018 - $27.95 - Programming Elixir 1.6 (Current version is 1.14)
2018 - $27.95 - Craft GraphQL APIs in Elixir with Absinthe
2018 - $26.95 - Functional Web Development with Elixir, OTP, and Phoenix
2018 - $24.95 - Learn Functional Programming with Elixir
2018 - $24.95 - Adopting Elixir
2015 - $11.00 - Metaprogramming Elixir
2014 - $27.95 - Seven More Languages in Seven Weeks
https://www.humblebundle.com/books/elixir-programming-pragma...
19 books for around 18 us dollars (at the time of this comment it had 9 days left)