There are a number of commercial facilities on the Cryosphere, these are the interesting ones -
|sells basic equipment
|sells more advanced equipment (Warrant Officers and above only)
|sells life insurance! (see 'INFO INSURANCE')
|sells first aid equipment or treatments
|stores money for safekeeping (see 'INFO BANKS')
|sells simulator training crystals
|sells simulator game crystals
|sells drinks and some junk food
|sells tickets for long-haul flights
|can rent out private quarters to players (currently at no cost), and sells furniture to fill them with
To find these, be sure to use the map command on station.
In a shop, you can type list for a list of things that it sells, and then buy to buy a particular thing. You can also preview things. If there's more than one shopkeeper in a location at a time, you'll have to specify from, for example, 'list from bert', or 'buy carrot from andy'.