books....

If I could I would not... If you got your money for nothing you would not value highly what you bought with it... If you buy wisdom for nothing you will not find it, nor work to seek it out and give it light... The rich- no matter how intelligent can never find wisdom... Only those who work at every step in the process can make sense of their place in the process of learning as the salvation of life from slavery... What I pay for books is often quite little, and the sacrifice of place for them is more considerable; and yet together it is enough to make me appreciate that what humanity has suffered to have knowledge is not the tragedy we endure to scorn wisdom... Truth is life, and knowledge is truth, and time is all these things... Do not expect anything without sacrifice, and reject the notion..

Check your local library -- most have digital media branches now. Also...

The Gutenberg Project

Baen Free Library

The Philadelphia Free Library

i found a good book on the net and it costs aroun 80$....thats to expensive for me

For me too; but much treasure is trashed as having no value, and much trash is traded for a small treasure... Books are about like anything else in this world... To have some understanding of value we must already have some understanding to begin with... You may be one of those rare people who can appreciate a windfall as all hard earned knowledge is... Many people think the sacrifice of life for knowledge is only a means of easy profit.

Another nonprofit site based on creative common licenses and works of public domain:
http://www.archive.org/mediatypes-browse.php?mediatype=texts
Archive.org also has legal public domain music and movies/videos as well.