This is a tricky one, and the cost would be highly variable, depending on how the escorts run their business. I have run a mercenary campaign in which the players ran a mercenary cruiser. It was back in TNE, and I do not remember the specifics of how we calculated the expenses.
In MgT2, however, we have several figures to provide a basis for cost:
- Starship monthly maintenance cost (per escort)
- Crew salaries (per escort)
- Life support costs (per escort)
After that, you'd have to estimate what the patron's potential profits are:
- Is the patron conducting trade? What are the potential profits from freight, speculative cargo, and passengers?
- Does that patron have other sources of revenue during the voyage?
- Is the patron's voyage subsidized by other sources? E.g., perhaps the civil service bureaucracy of Pourne wants trade to run through the region and therefore diverts some of its tax revenue to would-be trader ships to ensure that this happens in the dangerous region that is the Outrim Void.
Next, what are the escorts' potential revenue sources?
- Flat fee per parsec crossed?
- Lump sum from getting to a certain destination? E.g., running the entire Florian Route and back.
- Does the escort also conduct a side business of transporting freight, mail, passengers, or speculative cargo? Perhaps the escort works in concert with a mercenary company who need to refresh personnel at some point along the route.
- Are they smuggling goods or information to add to their profits?
I would estimate the potential profits of the trader voyage and then determine how much they would be willing to cut out of those profits for security. Then calculate the expenses for the escort(s), after which you can estimate how much of a premium they would charge on top of that to make a profit.
I wouldn't discount subsidies from the trading parties on either end of the route. For example, it behooves the Imperium to keep the trade routes at least reasonably safe from piracy so they might divert some amount of their budget to supporting escort services. Likewise for the Florians, Aslan, or other potential beneficiaries of trade. If it isn't already profitable or it's hard to make ends meet for both the traders and the escorts, then some level of subsidies might exist from the parties that stand to make the most profit: the big powers at either end of the trade route.
If this all seems like a lot of overhead, delegate to the players and then just review their data. I find that it's good to give the players some "skin in the game."
