Is there a list of free homeschooling items?
Look into Homeschool Buyers Co-Op (www.homeschoolbuyersco-op.org). Here is a direct link to their free homeschool curriculum page: https://www.homeschoolbuyersco-op.org/free-curriculum/
They also often have free trials. My son actually learned to read on a free trial of Reading Eggs!
I have had much the same problem with finances! I don’t have kids that old yet, but I have been reading some things that might help. Power of an hour at mentoringourown.com is a really cool curriculum, and although it’s not free, it’s cheaper than buying most curriculum. And if you don’t want to buy it, you can do what I did and create your own that’s really similar and that matches your own family needs. That might work really well for your middle student.
Also, The Well-Educated Mind suggests high school students study first hand accounts for history, and those can easily be found at the library. You just need a certain amount of hours to qualify for high school credit. You’d have to check with your state requirements. Library programs could count for writing or literature. Or just combine your writing with history and science, and you wouldn’t have to buy a separate writing program. Maybe volunteering at a zoo or other free programs could count for science, and then you could supplement with appropriate books and writing assignments.