What is the best way to find a reliable pepper mill?
Most basic mills with steel grinders will be OK

What breaks them are


Overly aggressive grinding; just grind gently and your mill will last much longer
Keep them dry; do not use a pepper grinder over a steaming pot. Grind pepper into a bowl or plate, and then pour into pot
Old peppercorns; as they age and dry, they get tougher to grind, and wear most mills out pretty fast. Store peppercorns in very air tight containers, so they can't dry out more than they are meant to be dried
Avoid those coloured peppercorn mixes; whatever makes the light colours, are also very tough. Stick with plain black pepper
Contaminants; pour your peppercorns onto a white plate and check for small stones or twigs before loading into grinder. Also check for "insect parts", most local food laws allow some of these, but who wants them!


I have gone through a variety of grinders over the years. Some expensive, some cheap. Price was not a factor, usage and care seem to have been

Acrylic grinders generally die quickly, as the acrylic cracks as it ages. Solid metal or wooden bodies are better as they last longer in general, and keep the pepper in a light proof container (which all food should be stored in, or in a light proof cupboard)