Classics

Marx and Engels:

Wage-Labour and Capital and Value, Price, and Profit

Ludwig Feuerbach and the Outcome of Classical German Philosophy

Socialism : Utopian and Scientific

The Marx-Engels Reader, will save you time and money by having so many works in one place.

Grundrisse : Foundations of the Critique of Political Economy (Rough Draft)

Contribution to the Critique of Political Economy

Capital : A Critique of Political Economy Vol 1, Marx's classic work

Capital : A Critique of Political Economy (Penguin Classics) Vol 1

Capital (Penguin Classics) Vol 2

Capital : A Critique of Political Economy (Penguin Classics) Vol 3

Economic and Philosophic Manuscripts of 1844

The Holy Family, or Critique of Critical Criticism, what most Amerikkkans don't understand--materialism.

The Condition of the Working Class in England (The World's Classics)

The German Ideology : Including Thesis on Feuerbach (Great Books in Philosophy)

German Ideology, Part 1 and Selections from Parts 2 and 3

The Civil War in France : The Paris Commune

Class Struggles in France, 1848-1850

Eighteenth Brumaire of Louis Bonaparte

Peasant War in Germany

The Origin of the Family, Private Property, and the State, in the Light of the Researches of Lewis H. Morgan

The Poverty of Philosophy

Critique of the Gotha Program

Cologne Communist Trial

The Portable Karl Marx (Viking Portable Library)

Selected Correspondence

Marx and Engels on the United States
 

Lenin:

State and Revolution

Two Tactics of Social Democracy in the Democratic Revolution

What Is to Be Done? Burning Questions of Our Movement, why a vanguard party is necessary.

Introduction to Marx, Engels, Marxism

The Emancipation of Women; From the Writings of V. I. Lenin

Essential Works of Lenin : 'What Is to Be Done?' and Other Writings
 

Mao

Quotations from Chairman Mao Tsetung, the "little red book" over a billion people have.

Five Articles by Chairman Mao Tsetung

Go see some more options for Mao books at Amazon