Jane Austen is quite habituated with satirising the poor mindset of the society that thinks that marriage brings in good fortune for young ladies and secures their future with good means of wealth. Hence, her comment "But there certainly are not so many men of large fortune in the world as there are pretty women to deserve them", is extremely ironical.
And I think it's quite typical and Austen's special style to give a lot of information about a man's annual income, his inheritance of wealth and his acquiring a big plot of land.
This is also a novel that describes the protagonist's journey from a poor sailor's daughter to the mistress of the Bertrams' estate of Mansfield Park.