Hello loves! This is going to be something between a rational explanation and a rant. If someone reading this fears that this might be about them and their fanfiction specifically, NO, it's not. I've seen this is so many fanfics... almost ALL the fanfics that even mention anything related to money, cost, income, paychecks, or anything economic... that this applies to almost everyone who is writing Star Trek fanfic but who doesn't have a life-long grounding in Star Trek philosophy.
Here are a few things you need to know about economics CANON in Star Trek. This isn't a judgment call, nor a decree of whether it's the right way or the wrong way to structure an economy. I'm NOT telling you that this is the way the future WILL be or SHOULD be. I'm not even saying that this would ever work.
No, this is just telling you how it is in CANON:( Capitalism is DEAD. )
Here are some things that should NEVER be said or implied in a Star Trek fanfiction if you're sticking to canon:
1. Starfleet's "budget."
2. Any reference to a person's income or paycheck. Or alimony. Likewise, saving for retirement. Why do you think there are 100+ year old people in Starfleet? I'm sure they COULD retire, but if they love what they do, why should they stop?
3. The "cost" of repairs. (The limiting factors should be listed as "time" and "resources," and the limited resources should be things that are known to be limited in canon, like dilithium.)
4. Talking about people being "poor" or starving on Earth. (Tarsus IV was a disaster of extenuating circumstances.)
5. Any mention of people being unable to afford basic things like food, clothing, shelter, or medical care. (That doesn't mean that people like a young James T. Kirk wouldn't avoid going to a doctor out of sheer stubbornness.)
6. Competition for profit, unless you're talking about a Ferengi. (Now, people will compete for opportunities, prestige, and so on. If you've got, for example, four groups of engineers trying to design a new shield for space ships, they might compete to have their design accepted by Starfleet. That would be canon-compliant. However, a "lucrative" contract is not.)
7. Credits being used for essential things. And no, booze is not "essential," so using credits to buy drinks at a bar is within canon.
1. People still have personal possessions. This is a socialistic society, not a communistic society. It's just that the focus has shifted away from the accumulation of WEALTH. Restoring an antique car for the joy of it? Within canon. Accumulating 100 cars just so you can re-sell them for profit? Not within canon, and that mentality wouldn't be understood by a person of 23rd-century Earth in Star Trek canon.
2. "Menial" is re-defined. Remember Boothby
from TNG? The old groundskeeper at the Academy? He loved his plants, and despite the fact that he wasn't faculty, he was highly respected. Maybe we should re-think the concept of "menial labor" ourselves.
3. Maybe some people aren't "productive" by our current standards... but who said they have to be? Tell me how to put a price tag on a painting.
So... there it is. You don't have to like it, you don't have to agree with the philosophy, but if you're going to write Star Trek fanfiction, you need to be aware that you're NOT dealing with a capitalistic economics system. Love it or hate it, accept it or debate it - whatever you want. But just be aware that in Gene Roddenberry's universe, this is the way the chips fall.
Now, that's not to say there aren't inconsistencies. There's a lovely list of those inconsistencies to be found here:http://www.ex-astris-scientia.org/inconsistencies/economy.htm
But still... realize that almost none of the contradictions are found on Earth itself. And none of these things involve the price of essential needs.
I'll leave you with this: Live long and prosper. NOW... debate to yourself what "prosper" might actually mean in Vulcan society.