Excellent question. Of course, in this novel there are many characters who do not have financial concerns, such as Mr. Darcy, Lady Catherine de Bourgh and Mr. Bingley. Therefore I will restrict myself to talking about the Bennet family, and in particular, Mrs. Bennet, in this response.
Key to focus on is the way that, at least in part, it is economic reasons that are behind Mrs. Bennet's frantic attempts to marry off as many of her daughters as possible. Note what we are told in the first paragraph of Chapter Seven about the brute realities of the existence of the Bennet girls:
Mr. Bennet's property consisted almost entirely in an estate of two thousand a year, which, unfortunately for his daughters, was entailed in default of heirs male, on a distant relation; and their mother's fortune, though ample for her situation in life, could but ill supply the deficiency of his. Her father had been an attorney in Meryton, and had left her four thousand pounds.
The exact details that we are given clearly indicate how important money is. The way in which the property of Longbourne is entailed away from the female line adds new understanding to Mrs. Bennet's determination that Lizzie should mary Mr. Collins, no matter what her personal feelings are, as it would effectively provide for Mrs. Bennet and the rest of the sisters after the event of Mr. Bennet. Later comments made by Mrs. Bennet about the Mr. Collins and Charlotte "turning them out onto the street" when Mr. Bennet dies, although are clearly exaggerated, nonetheless accurately reflect the uncertain future of this family unless they can marry off some of their daughters well to provide for the rest. Economic forces are therefore shown to bear massively on the fortunes of this family.