Ahh, right. “Free shipping within USA” is what it says for me. Sorry about that, hope you’re able to find a copy!

I can’t find a scan anywhere of anything 4a or higher, but if you are willing to pay for a physical copy there are a few sellers on AbeBooks selling “Reach Higher Student’s Book 4A”.

For free textbooks outside of that series:

BCcampus Open Publishing: They provide a ton of free courses and textbooks on a variety of topics. This isn’t really piracy, but it’s got a ton of good information.

I did find one site that seems to have all the PDFs for sale, but I can’t tell if it’s a scam or not. I would recommend looking at some of the free resources available on BCcampus before attempting this.