The data from yahoo is JSON so it is basically structured data within unstructured data.I've scraped in my youth, and although a fun programming exercise, the problem is that when websites change format (and Yahoo does this often), your scrape code usually needs to change along with it. I gave up scraping a long time ago, because it just wasn't worth the maintenance headache.
If you scrape based on exact delimiters and their location then you will constantly need to rewrite your code like you said. If you treat the HTML like one big "string" then there is usually a keyword marker that can act as your "start of data". This is a way to keep your code more nimble.
I don't deny that this is a headache and a possible waste of time. We are not on a "time management" message board. If you want to spend your free time doing it then yes it is possible regardless of what api services yahoo shuts down.