reminder about Kindles and playing MP3 and Audible files. I know it's possible to play MP3 in the background but there is a learning curve for some but for an audiobook it won't remember where a person left off. I pretty much remember that for Audible books those don't(?) play in the background while reading. I don't remember about Audible in the background. But the Audible book player on the Kindle does remember where you were last listening. Reading along with the audio can be an issue if the book can't be played in the background.
No matter for either the MP3 or Audible option I would suggest an Audible compatible MP3 player over using the Kindle simply because they are better at it and they solve the issue of reading along with the book playing in the background. Audible usually has some sort of special when you commit to a 1-yr subscription. For most of last year there was a $100 credit on Amazon if you setup a new subscription. The credit was only good for an Audible compatible player or accessory for those players.
Last if it's not too personal for the OP can you describe your hubby's reading difficulty, it will help people form more cogent options for you. And really nobody here is going to be judgmental about any issues, we all love reading and know everyone has challenges in life. But too people understand if it's too much personal info.
EDIT: Seems the Audible+Amazon $100 credit is still happening here is the page:
http://www.amazon.com/gp/feature.htm...8&docId=598985
Hope that might help a bit!