'What grinder should I get?' is a question more people should be asking. Too many people are too fixated on the 'what coffee machine' question. The grinder is more important. Once you've got good beans and a decent roast, the next most important thing in determining coffee quality is how fresh the beans are and how fresh and good the grind is.
First things first: You can't get an acceptable (let alone good) espresso grinder under $150. Most good ones (some exceptions, with small compromises) are over $600. So let's assume you're making pour-over, Chemex, siphon, Aeropress or something similar. With that in mind, the requirements are a lot lower.
What you're looking for in an entry-level non-espresso grinder:
1. Burrs, not blades.
Conical is fine. Flat is a little overkill in this range. It doesn't really matter what they're made of (ceramic or steel). Blades tend to produce unevenly sized grinds, and the amount of work they do means a lot of heat is imparted to the coffee, destroying part of the flavor.
2. Coarse adjustability.
You want something quick and easy to adjust. Some grinders like to give you very fine grain control. This is overkill for non-espresso coffee, and in fact can be really a negative and really annoying if it takes many turns to make a change to your brew.
3. An electric motor.
Manual hand grinders are pretty good these days (I carry a Hario Mini Mill with me when travelling). But your hands jerk around a lot. This will lead to a massive distribution of big chunks and too-fine grinds. If you can stabilize the rotation somehow (see below), it's better.
With that said, here are some favorite options.
Three options: The traditional, the stylish and the geeky.
Option 1. The traditional: Baratza Encore
The Encore is the entry-level grinder from the Baratza range and it is good enough for a wide variety of coffees. It's widely recommended by coffee geeks as an entry level piece and will likely last for years. It's easy to use with uncomplicated controls, easy to clean and won't disappoint.
Option 2. The stylish: Bodum Bistro Burr Grinder
Bodum has established a presence in the market of simple and stylish coffee gear. Their burr grinder (not to be confused with the cheaper Bodum Bistro blade grinder) is good quality, fast and affordable.
Option 3. The geeky: Hario Mini Mill Slim with an electric drill
If you have a hand drill, or you just want to be different, try this hack. The Hario Slim, a good enough hand grinder, is a little wobbly if you crank it by hand. the wobbles from hand grinding can introduce uneven lumps in the grind. This is suboptimal - you want an even grind for an even extraction. A drill takes this wobble out, and gives you geek cred. The shaft of the Slim is a convenient six-sided bolt, so it will fit right into any drill bit holder.
- Can be dismantled to portable, normal hand-grinding format
- Has about 10-20 useful settings points
- Convenient pistol grip format.
- Makes you look like a coffee ninja
- The Hario Slim mill is available in many places for around $30 (here in First Line, Prima Coffee and Seattle Coffee Gear).
- The drill is either a sunk cost if you already have one, or is about $20 from IKEA or some hardware store.