The E-book of Avadhuta Gita - Sanskrit text with English translation was prepared from the material provided at http://sanskrit-texts.blogspot.com/2006/06/avadhoota-gita.html
I found a copy of Avadhuta Gita translated into English by Kanoo Mal and published in 1920, containing a long introduction and a biography of Dattatreya, who Kanoo Mal assumes to be the Avadhuta. This book is in the public domain and is a very scholarly work. Its only shortcoming is that it doesn't contain Sanskrit text of the Avadhuta Gita.
1. Avadhuta Gita - Sanskrit text with English translation
2. Avadhuta Gita - English Translation by Kanoo Mal