One of the things not to go cheap on is a light meter. The second is optics. Inaccurate readings, short ranges, color insensitivity or over sensitivity, ease of use, reparability, repeatability, these are some of the problems with cheap used light meters. Sometimes it's better to follow the guide on the film box than to rely on a meter that is misleading you.

You will start changing the developing time, change films, change developers etc. while the meter is all over the place. Finally you will even "bracket" exposures to try and catch the correct exposure.

Get the best you can absolutely afford from the beginning and you'll be ahead of the game. In wood working there is a saying; "you can't do great work without great tools".