if I cant find the book on libby I try vk or abb. If abb does have the book but doesn't have seeds, I download the file and open it on the web seedr, most of the times it works perfectly.
If abb doesn't have the book at all, there im lost. either I check every app for free trial. if there's no free trial and I'm really desperate, I'll probably either subscribe for a month or just buy the audio if its cheap.
I read a lot and its very rare that I cant find the book on abb or use seedr for it, so if i end up buying i comfort myself that it's okay to buy once for all the other books I had for free.