Where is the 30 thousand pound figure? I remember this conversation about a maximum between the colonel and Elizabeth but don't recall a minimum mentioned.
Quote
from chapter 33 of Pride and Prejudice
"Our habits of expence make us too dependant, and there are not many in my rank of life who can afford to marry without some attention to money."
"Is this," thought Elizabeth, "meant for me?" and she coloured at the idea; but, recovering herself, said in a lively tone, "And pray, what is the usual price of an Earl's younger son? Unless the elder brother is very sickly, I suppose you would not ask above fifty thousand pounds."