We present a duopoly model with vertical product differentiation and uncoveredmarket, where the distribution of the consumers' willingness to pay is non-uniform. By using a trapezoid distribution we solve explicitly for market equilibrium as a function of a mean preserving spread of the income distribution. We find that the relationship between the latter and all relevant market variables is typically non monotone, i.e. strongly dependent on initial conditions. Indeed, these influence the interplay of the two forces affecting each firm's demand and its elasticity: greater income concentration makes for new consumers entering the market and redistributes demand between