I maintain a similar project for SoundCloud called SoundScrape: https://github.com/Miserlou/soundscrape which I started for a similar reason, to save my own 'likes' and tracks that I've made and my friends have made.
SoundCloud made this very easy, as they had an API which exposed the endpoint MP3/WAV location in a field. The tool used an API key provided by SoundCloud to fetch the response.
Overnight and without warning, they removed that field from responses, changed the terms of service, banned my application for terms of service violations, and deleted all of my personal music and likes because I had used my own account to create the API key.
I was very angry at the time since all my my music got deleted, but these days I'm just sad. Things like this have little by little destroyed all of my enthusiasm for technology.
I want to be a carpenter now.