Spaceships: Hulls and Airlocks
1. Vehicle airlock is at technological level six, takes up to two spaces, and costs two kilostarbux.
2. Compared to the additional airlock at minimum two tonnes, and one tenth of a megastarbux per tonne.
3. And then you have technological level nineportable airlock, or the Portairportie®, a flexible pressure tent kept rigid by a collapsible frame, the portable airlock has two openings and can be attached to a bulkhead to create an emergency airlock ... most commonly used when cutting into a starship hull for rescue purposes, preserving the environment inside, but can be also used to seal a building against NBC conditions ... big enough for two vacuum suited Travellers to use at once, and is reasonably robust ... comes with a small air bottle to initially inflate it, but then relies on pressure from the area being cut into to remain inflated. Weighs eight kilogrammes and costs a kilostarbux.
4. Or you could have a vacuum proof corridor, two hatches, and an air suction device.