The first Saw_movie ended up making dozens of times what it cost to make.
https://en.wikipedia.org/wiki/Saw_(2004_film)#Filming_and_post-production
https://en.wikipedia.org/wiki/Saw_(2004_film)#Full_Disclosure_Report
Saw 1 (2004) Ending https://www.youtube.com/watch?v=sxjlksJgq90
It's perhaps one of the most gruesome and disturbing movie series ever.
https://paranormal-intersection.blogspot.com/search?q=The+Saw+Movie+Series