I googled all but the Orthodox material I listed so far and virtually all is readily available to order.......for now.
Don't use Google; look them up on Amazon.
Look at the lowerst price from a private seller, not FBA, in your condition. Your condition is going to be VG unless there is writing in the book, in which case Good. Also look at that Amazon sales rank - any
book 1 million or below will likely sell in 6 months. 5 million and below probably two thirds of them will sell in 12 months.
If you search around on Amazon, you can open a seller account. There are fees to do this, but only if you sell a book. Understand the fees, vacation settings, how you are charged for shipping, shipping speeds and costs, etc.
FBA is fullfilled by Amazon. If you pay $40 a month, you can ship your books to Amazon and store them there. The advantage is that Amazon ships to the customer so it gets there very fast and the customer, if they are Prime, is not charged for shipping. So the price you receive for the sale is usually higher, sometimes a lot higher due to supply and demand.
Don't sell books FBA until you have lots of books listed. It requires a considerable time and money investment (shipping and storage costs, etc.) Its not for most people.
What you find about used book prices is that most fiction, other than classics, wont' sell and has little resale value. Maybe a few bucks but that is a wash with transaction costs.
Nonfiction can work. What you will find is that the more niche the subject can bring higher prices. This is becaue they were never printed in large quantities. There are a billion copies of In Search of Excellence or Rich Dad Poor Dad or The Millionaire Next Door available at used bookstores, but very few copies of Roosh's books. I once sold a book about lapband (gastric bypass) surgery for $65 that I got from the "free" table at a used bookstore. It was too niche for them to use up valuable shelfspace but was printed in low quantities so demanded a high price on Amazon. Textbooks that are current also go for a pretty penny, as well as books that are required reading in college but not a text book per se.