AIFV costs, should them be lowered or not?

[narwan]

No, I don't think so.
They seem too expensive because you pick an example in which they are clearly the inferior weapon system. In this game, all depends on what system has the edge over what other.
Put those same ATGM-cannon-TI-stabiliser-ERA IFV against a mixed of force of slightly older tanks (like M60's, Leo 1's, etc.) lacking TI and basic APC's and your IFV's (with their ability to fire through smoke and powerful weapons and infantry to do the spotting/securing for them) can slaughter the opposition.
You can't base the validity of the cost of a unit (type) by comparing them to one or two other types. It is determined in relation to all other units in the game. A tiger tank and a T34/85 (without HEAT) are close together in price even though the first is much better in direct confrontation. But against a platoon of infantry the Tiger isn't much better if at all so the price from that POV should be about the same as for a T34/85.

If you happen to find yourself in a situation where the enemy has a cheaper unit that can kill your more expensive ones or your same cost unit can't kill his while his can kill yours you're just out of luck. It happens.

But I will agree that modern IFV's are likely to suffer in this game and you're often better off getting another force mix. But sometimes they are the right choice.