Personally, I stick with manual spice grinders that are hand held. I use a basic two piece grinder by SharpStone to grind my spices. It's high quality. Made from hi-quality aluminum and CNC machined with razor sharp grinding teeth which shreds quickly and easily. An intelligently placed o-ring reduces friction and wear.
It doesn't matter if you buy SharpStone or some other brand, as long as you ensure the product is food-safe. Check out Kannastor, Chromium Crusher, Mendo Mulcher, and Space Case spice grinders.