when I began playing piano - 40 years ago - there was no internet and it was very difficult for me purchasing scores, particularly because I lived in a rural environment, as I do today. Nowadays it's much easier getting musical sheets, but often they are very expensive.
As a piano teacher I often searched for inexpensive sheets and books, but mostly in vain. My students often don't have so much money. Furthermore, very often quality and readability of free musical sheets is very poor.
All this is the reason why I began making my own sheets of music. One day I got to know Lilypond, a very nice piece of open source software. After quite a bit of learning, Lilypond has become an easy usable software giving professional results.
You can find some of my own editions here on IMSLP.
Please have a look on my website where you can find a lot of free scores for piano: http://klaviernoten-viktor.de