Their default build speed is too high! 18 million each is an acceptable price.
But the building cost of over 5k per second? Ridicolous in how often I have to start and stop its construction without killing my economy.
I understand that having a build cost of 2K per second will have it build for 2 and a half hours, but nothing is stopping you from using engineers to build it faster.
In the meanwhile, I can build:
Armor nullifier
Armor booster
2x OMD
Black hole machines
for less then a super fort in terms of rate. Right now its quite micro intensive.
[This drunk message brought to you by...frustration! A major innovator of human kind.]