I'm not a fan of Purism, the company behind the Librem phone, but it's fairly capable hardware for the price. The PinePhone is arguably even better hardware for the money, but it isn't quite ready for prime time on the software side. Gone are the days where a $300+ device is too weak or slow to use daily.

A better tactic would be to purchase one of the few Android devices that are fully compatible with either Replicant or LineageOS, or a phone that can run Sailfish.