In a thread a bit lower, it was discussed whether or not Anne had a dowry since Sir William said that he would "do nothing" for her. That leads me of course to think Elizabeth would be in the same situation. Surely even Sir W would not cut out Anne for Elizabeth's benefit (though thinking about it, I wouldn't be surprised, but I would think LR would make more of an issue of it.)
The question has been raised elsewhere about whether Mr. Elliot was rude not to come to visit Kellynch and also whether in truth he disappointed Elizabeth. To my mind, there seems to be only expectation on her part, unlike let's say Darcy who was expected not only by the aunt but perhaps by his uncle and maybe even his mother to have married Anne. I always wondered why Col Fitzwilliam or his brothers (we know he had at least one) were not called upon for that... Perhaps it is a plot hole but most definately it is off the subject here!
Anyway, back to Mr. E and Elizabeth. It says that Mr. Elliot "purchased independence by uniting himself to a rich woman of inferior birth." So to me the words purchased independence implied that he did not have it before his marriage. So if he had nothing to recommend him but being the future Sir William and Elizabeth had nothing to recommend her but being beautiful and the daughter of a Baronet, how would that marriage have been any less imprudent than that of CW and Anne? At least CW had the chance of making his fortune, however remote LR considered it.