...I don't think we really know at this point how wealthy (or not) LR actually is. Her clothing, possessions and house are not described in detail. We just know that she is well-bred, enough to be a suitable companion for Sir Walter and his daughters. Her manners and cultivated mind lead us to believe that she is or was wealthy enough to have had a decent education in her youth at least. The fact that she "had been brought, by strong attachment to [Lady Elliot), to settle close by her, in the village of Kellynch" could swing either way -- she could either have been left sufficient funds that she could leave her husband's home after his death and settle wherever she chose, or there may have been a financial attachment to the Elliots as well.