From a realistic point of view we should also remember that the rebellion is largely driven by ideology, not salary. They are fanatics, so the expenses a fighter might create will only come down in terms of supplies or items which the rebellion cannot generate on its own, or in terms of opportunity costs. Other costs for maintenance etc. might be disregardable as your workforce largely works for free.
Opportunity costs are irrelevant as long as your fighter rooster has not reached a size where your fighters outnumber your pilots. Till that point, you will be happy about any fly-able spacetrailer with onbolted blasters which you can get, as it increases your fighting value.