Reddit reviews Castle in the Air

I purchased all my books on iTunes, since it was easier for me. But I can link them, and you can go from there :)
When Marnie Was There
#1 A Wizard of Earthsea
#2 The Tombs of Atuan
#3 The Farthest Shore
#4 Tehanu
#5 The Other Wind
Tales from Earthsea
Howl's Moving Castle Kindle that includes the trilogy for $2 or Howl's Moving Castle physical
Castle in the Air
House of Many Ways
And going to cheat and link the complete set of The Borrowers, since it's pretty cheap.
Honestly, if you are looking to purchase elsewhere, the authors are really all you need to make sure you are getting the correct books.

I recommend:

1. The Abhorsen Trilogy by Garth Nix
   
   
2. The Bartimaeus Trilogy by Jonathon Stroud.
   
   
3. The Chronicles of Chrestomanci series Volume 1, Volume 2, and Volume 3 by Diana Wynne Jones.
   
   
4. Howl's Moving Castle, Castle In The Air, and House of Many Ways by Diana Wynne Jones
   
   
5. Tamora Pierce's entire canon. I especially recommend The Circle of Magic quartet, The Circle Opens quartet (both set in same universe); and the Immortals quartet and Trickster's Choice/Trickster's Queen duet (both set in a different universe).
   
   
6. Classics, like the Harry Potter books, The Giver, and The Hobbit.