the economy need more things like supplies ship that the captain can buy at cheap prices, vending the things to the bars, medbay (in that case the Head of the medbay can pay it at an higher price, vending it for a more higher price. this also work for bartender, cooks etc) etc. and everyone make a little bit of profit from that. in that way the captain or who manage the money can pay the crew of the ship, so the crew spend money in things that they need and the circle restart. it's only a fact to find a balanche (maybe making a fixed quantity of money that can be reduced or augmented thanks to tourists and other non-crew members). but in this case we also need banks, that can administrate the funds of the richest people (if they're offline from like one day maybe) giving some money to people that request it and that can pay the debts. but this need a loot of work, coding etc. to build a solid economy system, because you can't make a thing like this based only on what the server actually has, you need to implement also more things, more areas in the map etc.