Buying something just to preserve it

I'm certainly not going to buy something from a piece of fictional media that I personally dislike just to preserve it, but there have been times where i've spent more money then I usually would because something is so rare and I have no idea when i'll ever see another copy of it, like the California Dreams novel "A California Night's Dream" that thing is so ungodly rare that I had spend 125 bucks to get a copy from Etsy because it wasn't like I could count on another copy showing up anytime soon, same with some rare movies i've bought to get ripped such as Lights Camera Murder.