Same story here, I can be used films on DVD for €1 at many charity shops. Boxed sets of TV shows are €2-5 depending on size/popularity.

The only downside is that I've noticed that the used DVD sections are definitely getting smaller. I guess fewer people are donating their collections these days.

I've bought a couple of DVD sets from Amazon, used, but the prices there aren't so competitive. Still it's nice to have physical media, with real/original soundtracks.