cellio | daf bit: Ketubot 10

We learn from the mishna: a maiden's ketubah -- that is, the amount she is due should the marriage end -- is 200 zuz, while a widow's is a maneh (100 zuz). What of a maiden who is a widow (that is, one who was betrothed but he died before their wedding day), or who is divorced, or who was released from a levirate marriage? Her ketubah is also 200 zuz, and he can bring a charge of non-virginity. (10b)

We learned from the first mishna of this tractate, which I wrote about last week, that a man who finds that his wife wasn't actually a virgin after all (but said she was) can go to the court the next morning. This is because of the difference in the financial obligation for these two cases.

Why only 100 zuz to a widow/divorcee?
What's that in today's dollars?