Endlessly can now be purchased as an audio book through audible.com. Here is the link:
http://www.audible.com/pd/ref=sr_1_2?asin=B00CJ15VV6&qid=1367297658&sr=1-2 
It may take a few more days, but you will be able to purchase it on Amazon and iTunes also. 
How To Kill Yourself should become available within a few days as an audio book. I will keep you updated.