You know what I want a second hand paper shredder for? Plastic.
For a long time I've wanted to recycle plastic for use in a 3d printer. You can either build a machine to make your own filament, or make a 3d printer that runs on small plastic chunks. A cross cut shredder might be able to be modified to be used to shred pieces of plastic if large chunks are broken down first somehow.
Sounds like your biggest problem is an organization problem though. Is it really better to throw some shit out for some asshole to put it in a hole in the ground? Nah. It's better to figure out a way to reuse it, or someone else that needs it. So maybe you need to do some spring cleaning and organization. And maybe organize a schedule as well. Throw out the stuff that needs to be thrown out. Recycle the things that need to be recycled. Give away stuff that can't be sold, if it can be, and you don't need it. Frame the sentimental things or put them on a shelf. And all the shit you don't wanna throw out, organize it and put it in boxes and shit.
Spring is just around the corner. Perfect time to start some Spring Cleaning.