Looks like you picked through them pretty thoroughly.

I would also mention The Search for Planet X at $29.99, which if you could get for $20 would be an amazing deal (compare to GameNerdz at $34.97).

https://www.amazon.com/The-Search-for-Planet-X/dp/B085B21JD1

I also noticed D&D 5e books seem to be a good deal even before 1/3 off, but I haven't spent much time price comparing those.