Where to find level graded books?

Recently I've come across LingQ and I found it great, but the free version is very limited. I live in Brazil and, at least here, the price is kinda steep. I'm a student so I don't have too much money to spare on something I don't really know I'd use on the long term, so I wanted a site that has level graded books so I can read something for my level, at least on my target language, which is german.