[Edi]

That's up to personal preference. I chose 30, because all the units that have pathcost 30 already have at least two paths so adding a couple more low level ones isn't too expensive. But it is arbitrarily chosen. It could be 20 and it would be no problem.

A note about the Lawgiver: Listed as Rainbow despite pathcost 50 due to having a physical rainbow chassis and 3 paths to start with. Otherwise it would not fit in any category.