I mean, I know you're looking for piracy sources, but the 3D printing sphere is pretty much full of tech hippies.
This may go against the spirit of this server and all, but if you're just looking to print for personal use, there's a very real possibility that you can just ask.
I've hit up a few people before, stating that I wanted to print their STLs for my own personal use and sometimes they said no, but more than half the time, they just let me have it.
Usually something like:
"Hey, your project looks really great! I've been on a bit of a tight budget lately, but I do have my old printer and some filament lying around- would it be possible to get a copy of your STL files pro bono?
I would love to get my hands on it, and will definitely post a make to your page!"
(It definitely helps if you have some quality finished product images, so you're kinda free advertising for them)
I don't make the personal choice to pirate, (and I'm not here to judge) but I figured my kinda approach still may suit your needs.