150k for a black leveling is really really cheap. a single combination over level 70 is somewhere between 12 and 15k. (not sure exactly , and i'm too damn lazy to check).

From level 70 to 99 , u need 91k exp. Assuming you use just plat armors alone (+3 black fairies) , that means more then 11 combinations. Assuming 11k gold for each combination , u will pay over 120k just to level your black from 70 to 99 , and that's assuming u do it with platinum armors and 3 black fairies alone.

To level a black from level 1 to 99 without using plat armors can cost over a milion mate.