By the Base Conventional Infantry Costs And Availability table on page 282, the C-bill cost of a platoon is multiplied by 5 if it has "Anti-'Mech Training". Given that all non-mechanized infantry has an anti-'Mech skill under Total Warfare rules -- which can be improved through experience just like Piloting/Driving and Gunnery skills can --, at what point should this modifier be applied? If it really depended on just crossing a certain anti-'Mech rating threshold, that would make this the first and only time in the construction rules that I can think of in which skill impacts a unit's cost at all, let alone results in a sudden 400% increase upon reaching a certain level...