@The-Goosh
Actually, it was a matter of working backwards.
Infantry and Mechanized Infantry are the exact same. Therefore, the extra $1 for Mechanized Infantry had to be for Mobility only and that gave me the cost for one additional movement point for both Mechanized Infantry and Armor.
One thing that I took into consideration was that Infantry had to be the best Buy due to their amazing defensive capability while Armor, while very necessary, was probably the most expensive unit available and had to match its cost exactly. In other words, Armor must be priced just right as people still Buy it but know it is expensive so it is bought in limited quantities.
Knowing that, the next step was to determine Firepower Cost. After examining the numbers, and trying various amounts, it became clear, for Land Units, each Firepower Pip was worth $0.5.
Firepower with Mobility included:
Infantry $1.5
Mechanized Infantry $2.5
Artillery $2.0
Armor $4.0
Seeing that Armor only needed a Hit Point cost added for completion that gave me $2.0 per Hit Point. Which fit in perfectly with the other units.
Firepower with Mobility and Hit Point included:
Infantry $3.5
Mechanized Infantry $4.5
Artillery $4.0
Armor $6.0
The only thing left to add was Special Attributes. Artillery adding 1 Pip to infantry was obviously worth $0.5 and that finished things off.
Hope that helps…