Manic panic makes a PPD-free black and brown dye, I believe. You'd have to email them and ask to be sure, but they do have a smallish line of natural hair colors. You could get pretty much any color by mixing the non-crazy colors with say, their dark red or blue with the black.

I'd caution against using PPD dye, especially if your hair grows quickly and would require dyeing very often. If you did end up having a bad reaction to it, the longterm reprecussions of that could be pretty severe. The hennaforhair page talks about the use of black hair dye causing someone who had had a "black henna" (PPD hair dye, not henna obviously) design done causing severe facial swelling and other issues. While your hair would be getting most of the dye, not your skin, if you'd be dyeing often the reaction could be similar even if it took longer to happen.

Granted, lots of people have used PPD-based dye for their entire life without a problem, but the risk seems rather high to me personally.

I wish you luck and non-gray hair in whatever you choose