So I bought the books and bought the lunches.
The most effective way to learn something thoroughly is to teach it, and I was the facilitator for the book club, leading all the discussions and planning things out. The thousand dollars or so I spent per book, which won me sufficiently motivated study partners depending on me to lead, offered much more value than money spent on typical coursework or conventions.
Never mind the value I was providing for the company (lost on the new management, but I felt good about it nonetheless), spending that money was justifiable solely in terms of creating a maximally stimulating learning environment for myself.