As others have said, it's certainly justifiable for anything with rewatchability. You can find 1080p Bluray players at thrift stores for under $20 (it took some patience for me to find a relatively newer one that was more compact and didn't have a slow interface), and Blurays are usually under $5.
I've come across sealed Blurays or even the occasional former Blockbuster rental so it's actually kind of fun in a record-crate-diving sort of way, if you're into that. But of course you can always just buy new, which you'll probably have to do in some cases: the odds are against me finding Koyaanisqatsi at the thrift, let alone the Criterion Collection Qatsi Trilogy, but I'm okay with that.
I've come across sealed Blurays or even the occasional former Blockbuster rental so it's actually kind of fun in a record-crate-diving sort of way, if you're into that. But of course you can always just buy new, which you'll probably have to do in some cases: the odds are against me finding Koyaanisqatsi at the thrift, let alone the Criterion Collection Qatsi Trilogy, but I'm okay with that.