Marxists argue that inequality is part of the structures of both agrarian and capitalist economic systems. Pride and Prejudice takes place, historically, at the juncture of both systems, with Darcy representing the agrarian "landed wealth" economic system, and Bingley representing the "new money" of capitalism (he is the son of a wealthy industrialist father from the "North," the word "North" a short-hand for a mill owner). Both economic systems oppress women and force them into a situation where they must sell themselves to the highest bidder in order to survive. We see this throughout the novel: Mrs. Bennet spends most of her time in desperate matchmaking because she knows her husband's death will throw the family into genteel poverty. Charlotte likewise understands that she must make a match with a man she thinks ridiculous or live at the mercy of her brothers, who may not want to support her. Elizabeth recognizes the Lydia is ruined if she does not marry Wickham, for a non-virginal bride is "damaged goods" in a culture that sees a woman as a commodity to buy on the marriage market.
Beyond female oppression, we see in the many protestations of the housekeeper at Pemberley, Mrs. Reynolds, that Darcy is a "liberal" (financially generous) master, that this behavior is not necessarily the norm. The agrarian aristocracy can easily oppress the people--farmworkers--on whom its wealth is based. In both worlds, upper-class women are denied the opportunity to work for a living while lower class women are exploited, leaving both groups with few options.
A Marxist reading would argue that in a post-revolutionary Marxist state, women and workers would not have to live in fear of poverty or humiliation, because all people would be guaranteed respect, the chance to work and sufficient resources to live. Money would no longer corrupt and deform human souls as it threatens to do in Pride and Prejudice.