I have to say I agree to this issue as well. On trying the newest release out, I was eager to get to grips with the new Mist Elf Necromantic powers, but considering that the power costs clay and uses it up with a reasonable failure rate anyway, having to also spend points of Mana in order to create reasonably weak creatures seems entirely unbalanced towards the weak side.
In comparison, Necromancy allows for the raising of a ghul with 1 point of Mana, a faster creature than the homonculous that also causes paralysis with melee attack and regenerates itself.
I wouild say that the costs for White Necromancy should be at maximum equal to those of normal Necromancy, starting from 1Ma with the Clay Statue to match the Ghul and with the first four levels (Clay Clay Stone Stone) costing 1, 2, 4, 8 respectively. Perhaps keeping homonculi as a skeleton/zombie equivalent (always costs 1Ma to raise, available to non-Necromancer classes, and possibly also to non-Mist Elves?) and adding a couple of more powerful levels to finish out the necromantic power.