In the errata thread for Interstellar Ops it gives costs for the construction on units by weight.
p. 353, NEW COMBAT COMMAND COST TABLE.
Replace Combat Formation section of the table with:
Cost (RP) by Weight
Combat Formation | Light | Medium | Heavy | Assault |
BattleMech Regiment* | 16 | 24 | 30 | 40 |
Aerospace Wing | 8 | 12 | 15 | 24 |
Armor Regiment | 8 | 12 | 15 | 24 |
Infantry Regiment | 6 | 6 | 6 | 6 |
Artillery Battalion | 5 | 5 | 5 | 5 |
Most of these entries match up with the ISW Combat Command Conversion Table in Campaign Operations.
Except Assault Aerospace isn't listed in the CampOps table, but Dropships are.
Does the cost for Assault Aerospace refer to Dropships?