Most cameras have this built-in to some extent ... and does so reliably. A neewer F500 field monitor with its sun shade in place. The F500 comes in at $159 / £164 (although deals can be had ...

and supports a focus assist light that automatically lights up under dim light when the camera is unable to focus 【Built In 2.4G Wireless Q System】 Wirelessly trigger NEEWER Q4 Q3 Z1-S Z760-S ...

Neewer has a reputation for building ... I'm not a fan of bottom-edge ports on a monitor, as I like to have it close to the camera. Using the included bracket doesn't help either, as it sits ...