Responding to this although each of my answers here just gets swallowed into oblivion by the number of new posts.It makes building a 2nd t2 or t3 port take twice as many lower tier settlements and hubs to build. This makes it so that a lot of systems will never be able to have more than 1 large port unless you started the colonization with one of the larger ports since it bypasses the point requirement.
This is based on my own actual experience in combination with CMDR Mechan's observations.
It makes building a t3 space or ground port cost 12 tier 2 points. That's double
It makes building a t2 space port cost 5 tier 1 points. That's not quite double
It does not increase the cost of anything else
It does not start when you get to 10 constructions.
The initial port/outpost you build is not included in the calculations.
The increase starts after you have started your second additional port - tier 2 or 3 space (orbis, ocellus, coriolis, asteroid) port or tier 3 ground port.
I have 10+ constructions, started with Coriolis, built 11 other things and then another Coriolis, at that point there was no increase. once I started my T3 ground port the costs increased.
I don't have data for 2 x tier 3 ports, but given the above its possible you could have 3 tier 2 or 3 ports before the cost increase, or 2 if you started with an outpost.
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