I would like a book or PDF file that teaches the basics of category theory using basic abstract algebra (groups, rings and modules) as an example.
For me, the ideal book is "Algebra: Chapter 0", written by Paolo Aluffi. I'd like something as similar as possible to this book. I don't use this book because unfortunately I don't have money at the moment to buy it. I also don't want to download an illegal copy of that book because it is piracy.
Could somebody please indicate me some free (or at least cheap) material similar to that book?