Miss Elliot did not have as much as 10,000 pounds (see my post below). 10,000 pounds would have been considered enough for a baronet -- re Mansfield Park -- chap 1 --
"About thirty years ago Miss Maria Ward, of Huntingdon, with only seven thousand pounds, had the good luck to captivate Sir Thomas Bertram, of Mansfield Park, in the county of Northampton, and to be thereby raised to the rank of a baronetís lady, with all the comforts and consequences of an handsome house and large income. All Huntingdon exclaimed on the greatness of the match, and her uncle, the lawyer, himself, allowed her to be at least three thousand pounds short of any equitable claim to it."
Maria Ward, who became Lady Bertram, was considered very lucky because her dowry was only 7,000 pounds, and that was considered 3,000 pounds short of what should be a dowry (of 10,000 pounds)when marrying a baronet. And moreover, Miss Ward was not a baronet's daughter herself, so she should have a larger dowry.