As a beginner (with or without basic knowledge) it’s important to build a solid pianistic foundation through a well-structured piano method. I recommend Faber Piano Adventures (for children and adults) or the Hal Leonard piano method (for children and adults).
I mostly use Faber Piano Adventures which consists of several levels. You can work through all the books in a few years, depending on how much time you invest.
After that you can decide depending on you stylistic interests, where you want to put your musical focus (Jazz, Pop, Classical, Improvisation, etc…)
To save you some time and research, I offer to buy the necessary materials at a local music store and then pass them on for the same price.
In general you can take roughly €50-€100,- of yearly expenses into account for sheet music.
In the creativepiano express program a flat rate of €40,- is charged per semester for method books, sheet music and studio licenses in addition to the semester fee.
Furthermore there is the possibility of borrowing music books from my extensive music library. This is useful if only a single piece from a certain music book is played and it is not necessarily worth purchasing this book.
You can find a repertoire selection here.