I bought so many Blu-Rays in the last couple of months that they don't fit on my shelves any more.
I own 824 movies on Blu-Ray and a few TV-series although not thaaat many and not always in a complete set (Breaking Bad, Fringe, Lost, King of Queens, Big Bang Theory, Homeland, Sherlock).
About 700 of them were used and I paid between €1 and €3.50 for each movie. While the individual prices are quite low they will add up quickly.