Let's get a bit more concrete. As an example, Sisko's father runs a restaurant. Seats at that restaurant have to be a finite resource (because they require labor), and so would not be "free" to everyone—the owners get to choose whom they give it to (which brings up the interesting question of whether the Federation would have anti-discrimination laws, but I digress). Let's say Sisko chooses to feed people in his neighborhood; choosing to live in that neighborhood is the "price" his customers pay for his food. Similarly, Picard's brother makes real wine; that would also be a finite resource (as opposed to synthehol, which is free to everyone). From the context, it seems likely that Picard the elder distributes his bottles to friends and family; a relationship with him is therefore the "price" of a bottle. Art, live theater, music, etc.—anything involving human labor would constitute limited resources. Presumably, if you wanted that kind of thing you could sign up to get it—if there was too much demand, there would have to be a waiting list.
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