I'm not sure Georgiana's 'fortune' is the same thing as the money settled on Bingley's sisters. I believe their money is more in the nature of dowries (though not, technically, those), whereas I've always thought Georgiana's money comes from her mother - she would have been at most 11 when her father died, so I doubt he was thinking about her getting married. My guess is Georgiana was 'given' Lady Anne's dowry (the few settlement contracts I've seen designated the mother's fortune to go to the other children, perhaps in this case after Mr Darcy died).
As I've said before, I think the most likely figure for Darcy's income is 10K a year. But if we're making a parallel between Darcy's fortune and Bingley's, 30K suggests Darcy's fortune is at most 6-8K (vs. Bingley's 4-5) and it suggests someone is a cheapskate, as 40K of 140K total got settled on the girls in the Bingley family, so Georgiana gets only half again as much as one Bingley sister? This is another reason I think it's an apples to oranges comparison.
As I've said before, I think the most likely figure for Darcy's income is 10K a year. But if we're making a parallel between Darcy's fortune and Bingley's, 30K suggests Darcy's fortune is at most 6-8K (vs. Bingley's 4-5) and it suggests someone is a cheapskate, as 40K of 140K total got settled on the girls in the Bingley family, so Georgiana gets only half again as much as one Bingley sister? This is another reason I think it's an apples to oranges comparison.