Excluding textbooks for classes, I bought this for ~$300 (several several years ago as a special treat)
Most of my collection is thrifted/bought from garage sales (for a quarter to a dollar usually) but I do have a handful of nicer ones.
30$, only because it was the mtg books that came from the box, cards,,,etc. i only did it until i cant justify buying it anymore, since i dont play mtg after hs.