It's only cheap for the very first controller or fabricator you hack. For your second hack it's 50% higher, equal in "cost" to taking a planet. For the third hack it's 50% more expensive again. At that point I have used 95 HaP to gain 3 turret controllers which cannot be lost, but nothing else. That's 5 "points" more expensive than capturing three planets which will also come with energy, metal and possibly other useful goodies. I don't think that's distorted. Hacking all eight controllers is frankly unfeasible. If you want all the turret controllers, you almost certainly have to capture some of them.
Cost of knowledge hacking grows up as well. To hack knowledge for 3 types of mark 3 turrets, you need to spend 142.5 HaP (actually more, since knowledge cost is 9750, not 9000).
