As someone in here already said, Audible is great. You don't even have to sign up for a membership, go on eBay and buy some of the cheap credits on there. I don't know how it works, but I promise it works! (
$1)
Using this method can get you books for about $1.50 each. Set up the Alexa to work for him, and all he has to do is say "Alexa, read Gone With The Wind" and it will start the book for him the last place he left off.
My boyfriend is blind and uses Alexa for this and it works wonderfully.
Also, I think you can buy a dot now for a lot cheaper than an Echo, and it still has Alexa on it, so I recommend that! Prime Day is coming up in July so if you're not in a rush, it's usually on sale that day.