My mortar and pestle works like a charm if the peppers are thoroughly dried. I have made a ton of batches this way. If they're not dry enough (brittle to the touch..easily crumble) then it doesn't really work. You guys with your high techness...sheesh!
I use an 20 year old Braun coffee grinder. Nothing fancy, just on and off. I can put whole dried peppers in there and the blades will turn it to powder in about 2-3 min of running. Now, I wouldn't want to do high volume amounts with it like you would for selling powders commercially, but for home use its perfect and cheap.
Hey that's what I use! Got it for free too! And yeah it powders quite well.