Grinders are definitely worth it. They're easy to use, just put bud in the teeth, place cap, and spin. I guess you could just press it down on your left hand and twist with your right, that should work.

I've got a cool one similar to Art's, but with a screen at the bottom and another chamber underneath. When you grind buds, there's always a little bit of the powder that falls off. So screen lets it go down into another chamber and it collects. Every few weeks, you can collect what's down there and sprinkle it into a joint for some extra-strength! It works really well, just gotta keep it clean with rubbbing alcohol.