How much you pay additionally to normal teching costs to get that AA?
Oh, that is right, ZERO.
Therefore, its free.
Really simple concept.
Oh and anvil RE LMGs have a cost since last year. Keep up with the changes.
Except that it isn't. If you buy a Shreck upgrade, you get a shreck + cold immunity. Which of these two is for free?
If you buy a unit which has a vet 1 ability, and it has to be unlocked in a tier, is that for free? No. If Bazookas would cost 0 Munitions, would they be free? No they wouldn't, because you need to unlock them first.
If you buy a car and get a bonus tire with it, did you get that tire for free?
Go into your university and ask a professor of economics or informatics what he thinks about this.
You buy a car, and to this car you get a tire. This tire is not free as you need to buy the car first. If the tire costs 100$, it would be the same as if the car would cost 100$ less.
The tire would be free if you could go to the guy, get the tire and return with the tire and everything else you had with you.