Everything is centered on the infantry unit which is 3 ipcs for a 1/2/1 unit.
For every additional movement a unit has add 1 ipc.
For every additional attack or defend value add 1 ipc.
For every three added on add a special ability (tanks are 3/3 special is blitz which is a movement).
If your unit is has the same attack move and defend value as another unit, but has an additional special ability, then add 1+ ipcs reasonably.
~
Examples.
attack mech are 2/1/2 units (attack 2 defend 1 and move 2) costs 4 ipcs. Does not pair with artillery.
marines are 2/2/1 units do not pair with arty. cost 4 ipc.
dug in defenders are 1/3/1 units, cost 4 ipc, do not pair with arty.
heavy transports are 10 ipc for 1/1/2 unit that can be taken as cannon fodder instead of being a 0/0/2 unit that cannot be taken as cannon fodder. (1 ipc for attack 1 ipc for defend 1 ipc to be used as cannon fodder).
If someone starts a debate about heavy transports, point at the cost and say it is not a unit you would like to lose, which is why in ww2 only 4 of those suckers rammed into something.
a fighter is 10 ipc, 3/4/4 unit. infantry is 1/2/1 you pay 7 more ipc for a fighter than an inf. It has specials that tie into other unit’s specials.
Early fighters are 8 ipc for a 2/3/4 unit.
Bombers are 4/1/6 cost is 12. they are a bit overpriced in regard to the rule of thumb, but their special is devastating. Industrial bombing is painful. Tactical fighters have limited bombing support, but when aa guns hit they can take the place of your bombers.
So you have to adjust the special costs accordingly.
~
Naval may seem funny
6 ipc gets you a 2/1/2 unit with a first strike special and a hide unless you have a destroyer, but limited to attacking naval. you spend 2 ipc for specials and 1 for extra movement.
destroyer is 2/2/2. you spend 3 ipcs for a special and 2 ipc for attack/move value.
cruiser is 3/3/2, 4 ipc for attack defend and move, but 5 ipc for the ability to bombard.
battleships are 4/4/2/2 units you send 6 ipc for attack defend and move, 11 ipc for the 2 hit and bombard (better value than cruiser, which is why many people argue the cruiser is the worst unit in the game).
Carriers are 0/2/2/2 units. you spend 13 ipc for the special to carry fighters and the tilt.
~
Heavy carriers just add 1 ipc for every attack / defend value you put on it
early subs usually cost 1 ipc less and have 1 less movement.
Every inrease of attack for naval that bombards should cost 2 or 3 more ipc. 5/4/2/2 bship could cost 22 or 23. 5/5/2/2 bship could cost 24 or 25.
All naval should have a special and appropriate costs. That is what makes naval fun.