Who decides price of older movies?

[bluDJ]

I'm curious as to who and/or how the price of BD is decided? There's been movies I loved, and wanted to add them to my collection. but when I see them as a release, I cannot justify paying the cost of $20-25 for a movie that should be no more than $8-10. Are they doing this to deter us from buying them in favor of streaming or is it some other gimmick?