While the actual monetary units and their exchange rates vary from place to place, it’s easiest to express them all in credits, a bitcoinage used as a medium of exchange across civilized space. In general, prices given in SWN are good for “standard” Strange Stars equipment prices with some exceptions, as discussed above. What you get for that price will be a bit different than in the default SWN setting: a common pistol, for instance, will have biometric identification, and a smartware integration for ammo tracking and maintenance. All of this applies to “standard” advanced, star-faring societies — which isn’t the only sort civilization players may encounter.
Remember that the SWN listed prices are good for fabricated equipment too, though you may pay a tax on a public fabber..