black belts cost anywhere from about $3 to $22 from what i've seen
i went to a few diff tkd schools and one of them charged $130 for a black belt test but i didn't like that school too much because he never failed anyone who did horrible
the school i currently go to is $120 for the black belt test which is held twice a year. other rankings only have to pay $40 for their tests. however.. people who have financial issues can have the fee waived or cut down a lot. everyone at my school knows this but no one i know has ever used it except when it comes to tuition. the thing i like most is that the money isn't being squandered away, i speak to my instructors freely between classes and they admit that they dont have much money and that they all live in apartments with room mates except for the head instructor who owns his own house.
no one can really complain about the tuition or testing fees which is quite fare because i know the location where the schools are, are pretty pricey. also, a lot of money is spent for students + instructors birthday parties which are held on saturdays, there's always free drinks, food, ice cream, and cake. also, every year there's an annual bbq where everyone can bring their friends and family for free, there's all you can eat food, drinks, snacks, and desserts.. so can't really complain