[deng]

Since you are explicitly asking for cheapest: a used Motorola Moto G7 Play can be gotten very cheap. Alternatively, a used Pixel 3a. You probably find something cheaper from Xiaomi, but I'd stay clear as unlocking the bootloader is not pleasant on these devices.

Personally, I would aim a little higher though. I run it on a Pixel 4a and am quite happy. (Don't get the Pixel 4/XL since those do not have a fingerprint reader but only Face Unlock, which the latest LineageOS does not support.)

[beretguy]

I tried looking for these phones on eBay - it’s a bit challenging to find unlocked refurbished phone that would work in my region from a trusted seller. Sometimes you have to take the leap of faith with a purchase and hope it works. It’s a bit of a headache…