An omnibus of the first four Mary Poppins stories by PL Travers is $2.99 at Kindle and Nook US. Not (at least so far) at Kobo US, where it is a whopping $17.99.
Kindle US:
https://www.amazon.com/Mary-Poppins-...dp/B00O70WODK/
Nook US:
https://www.barnesandnoble.com/w/mar...780544574755#/
Titles include:
- Mary Poppins
- Mary Poppins Comes Back
- Mary Poppins Opens the Door
- Mary Poppins in the Park