Texts which used to be (maybe still are?) used in Irish schools. Free, downloadable text files (audio files also exist, at least for Book 1):
Anseo is Ansiud - Book 1: http://www.gaeilge.org/AIA1
The link to the free, downloadable audio files for Book 1 seems to be broken, but I have the files themselves, if anyone wants them (just message me and we can figure out how to do that). If anyone finds a working link, please let me know.
Anseo is Ansiud - Book 2: http://www.gaeilge.org/AIA2
Anseo is Ansiud - Book 3: http://www.gaeilge.org/AIA3