I bought one book in February and spent $3 cash; my YTD total is five books and $8. Google promotions accounted for most of my purchases.
I feel pretty confident I've got this licked. The cessation of Kobo coupons was a huge factor, but there's also an element where I got jaded. My library is so huge that new purchases just aren't that compelling any more. I think I'm ready, tentatively, to start buying the occasional book on demand, just because I want to read it
now, price be damned. Well, within reason; I've got many, many hugely expensive books on my wishlist that will never be purchased absent a lottery win.