Bulk YouTube/SoundCloud MP3 Downloader

I keep every song I like as a Firefox bookmark like an idiot, split between YouTube and SoundCloud, and I’ve now amassed well over 500 of them I think. I’d like a small program that can run on my PC, read the bookmark file, pull each link, and save the audio as an MP3... (Budget: $10 - $100 CAD, Jobs: API, Audio Processing, Automation, Data Extraction, Data Management, Desktop Application, Python, Scripting, Software Development, Web Scraping)