But you should bear in mind the proviso that Marx elaborates in Poverty of Philosophy when he chides Prudhon and Bray for thinking that the exchange is unequal. On the contrary, he says, the worker is paid the value of his labour power at its just price - ie the price of the commodities that go to his subsistence.
It is wrong to insist upon an 'equalitarian' approach because this is precisely the real condition of exploitation
'Mr Bray turns the illusion of the respectable bourgeois into an ideal he would like to attain. In a purified individual exchange, freed from all elements of antagonism he finds in it, he sees an "equalitarian" relation which he would like society to adopt.
'Mr Bray does not see that this equalitarian relation, this corrective ideal that he would like to apply to the world, is itself nothing but a reflection of the actual world; and that therefore it is totally impossible to reconstitute society on the basis of what is merely an embellished shadow of it.' -- Jim heartfield