Meow2099 It's been awhile since I've put a custom OS on a phone but with things happening in the United States as they're happening I'm thinking that it's time to take back my privacy.
Well, you have found a bunch of people who share that interest!
Meow2099 I'm looking to buy used phone preferably $100 or less.
I suspect in that price range you would need to look at DivestOS. Note that most or all of the devices supported by DivestOS are out of vendor firmware support. This means that one should expect that exploitable attacks are in the hands of actors such as criminal gangs and state actors -- including, plausibly, remote code execution attacks.
If the day-to-day operation of a device is fairly private, but the security of the device is breached, that may be a substantial privacy reduction.
At present, a mobile device with privacy and security is a "pay extra" proposition.