I currently own and sometimes wear an indigo hakam from
Iwata. I like the way it looks and feels, but I will say that it will "smurf" things for quite some time, even if you do go and wash it in the washing machine as
Carol's article suggests; it'll leave your hands tinged with blue and if you take any vigorous ukemi (especially suwariwaza), it will leave indigo streaks on the mat which are a pain to get out.
I've seen the
Tozando brand indigo hakama and have heard good reviews from people wearing it. I haven't worn one yet so I can't comment on its quality myself, though.
As far as taking care of it goes, it's basically the same thing that I do for my 100% cotton
Bu Jin Design hakama. I always fold it after I wear it and wash it probably about once every six months to a year.
Hope that helps.
-- Jun