As Barry said, I have had good experiences using my Android smartphone with a reader app with good TTS. No need to create mp3s using this method. Ivona isn't available in the Google Playstore anymore (thanks a bunch, Amazon!) but my old version of Ivona Amy is still working OK on Android 7 at the moment.
However, if you prefer to take the record-to-mp3 option and you have a 'normal' Win7 PC then
TextAloud from NextUp.com would let you do this. They can also
sell you Ivona voices (individually or bundled) to work with TextAloud if you want to pay for them. What I'm less sure about is whether running Win7 on a Mac would run this combo OK. I have zero experience with anything Apple-related.