I agree that the best book to teach undergraduates is Duncan Foley's (1986).

There are some other good books on the subject written in the late '60s to
the late '80s you may wish to look at.
Ernest Mandel, Introduction to Marxist Economic Theory, 1973 (initially
written in french in the 60s). A great marxist scholar and
activist.
See also his introduction to the Penguin edition of Capital I and his New
Palgrave 1987 entry on Marx. BTW there is a reprint of the New Palgrave
entries in a separate little book called Marxian Economics (Eatwell,
Milgate & Newman Eds)
Meghnad Desai, Marxian Economics, 1979
George Catephores, An introduction to Marxist economics 1988 (He also
wrote a more mathematical book with Michio Morishima)
Ben Fine's Marx's Capital 1989 (3rd edn) (1st written in 1974)

Not for undergraduates but still great is I.I. Rubin's book Essays on
Marx's Theory of Value
http://www.marxists.org/archive/rubin/value/index.htm


The definitive site for Marxists texts and a lot of reference material
from Petty to Keynes and Bohm-Bawerk is www.marxists.org

Marx's own works are indispensable for any course.
The Communist Manifesto (I would recommend the anniversary edition with EJ
Hobsbawm's introduction)
The Preface to the Contribution to the Critique of Political Economy and
exceprts from Capital I. On the transformation problem there is a lot of
stuff from the original section in vol. iii to Sweezy's edition of
Bohm-Bawerk, Hilferding et al. and Desai's article Journal of Economic
Surveys, 1988, 2(4), 295-333 , or The Value Controversy 1981 (Steedman et
al.)

Braverman is indeed great on the labour process. His book (1975)started a
Bravermania in sociology and industrial relations and there is an
anniversary edition from the Monthly review press.

Nicholas Theocarakis