Well, Marx distinguishes between price and value. He then argues that price is a feature of the capitalist system, with the consequence that you can only build

Well, Marx distinguishes between price and value. He then argues that price is a feature of the capitalist system, with the consequence that you can only build a theory of capitalism on price dynamics, not a more general theory that would be able to talk about different economic systems. He then goes on to argue about necessary work and work that is spend beyond keeping just the status quo - the surplus value. And besides, your argument about expensive handbags is flawed, since they are status signifier because of the work of PR people.