How do I scrape an old website into a .CSV file for data migration?
I would recommend to use "Open Refine" for preparing your data!

Open Refine (formerly: Google Refine) is an open source tool, running on your own computer, that allows to perform data manipulation as you need for any CiviCRM migration project.

To get a quick idea how it works, you could take a look on these tutorial videos:

https://www.youtube.com/watch?v=yNccGtn3Wb0 (Introduction 1 of 3)

https://www.youtube.com/watch?v=45EnWK-fE9k (Introduction 2 of 3)

https://www.youtube.com/watch?v=5tsyz3ibYzk (Introduction 3 of 3)

The third video will show how to "add column by fetching URL's" - this should deliver what you need!

I have save hundreds of hours using OpenRefine during CiviCRM data migration projects. Of course, you will have a learning curve in using it. But this is one of the rare tools where you will save time already the first time you are using it.