The quote taken from Erasmus is: "When I have a little money, I buy books; and if I have any left, I buy food and clothes". This is very true for me. This is even how I behave when going to the supermarket.
Here is one thing I do often: buy books. There are always so many books I want to read ;-) I buy mostly non-fictionnal books. I love how we can use them to learn things, to discover new paradigms in various fields. My Amazon Wish List is full of hopefully good books.
Now I also buy ebooks. Not for ecology. Just because it's much more convenient to have them accessible on my computer which I carry all day long. I have a Kindle too.
Here are some books I recommend:
Maybe you love books. Maybe you also spend too much money on books. It's OK, it's an investment. Read them and after do your best to apply what you learned. Share them with your friends, lend them, offer them.