You can go with just about anything as long as it's stainless steel with a diamond shedder design and a keef catcher. 3" diameter grinders (or bigger) are a must.
I was gonna get a Chromium Crusher from Amazon but read reviews about fake ones and falling apart so I bailed on it and now I'm just confused.
I do know I want a kief catcher and something made strong.
I see Space Crusher everywhere, but thats a lil pricey for a grinder.