Each week's Reading Guide will specify topics to read about, including key words and concepts that students should cover. Although suitable pages in the above textbook will usually be indicated, students are free to use any textbook for these readings.
Because BIOL 234 has open-book tests, purchasing only an e-book may not be suitable because students will not be able to bring it to the quizzes, midterm or final exam. (In principle students should not need a textbook for these tests but most prefer to bring theirs 'just in case'.) However the e-book version of the recommended textbook does allow students to flag sections and pages for printing as a Study Guide, so this may be sufficient.
Any of the textbooks listed below would also be suitable, and they are likely to be available used, either locally or through Amazom. Many originally came with CDs and access to special web sites maintained by the publisher, but these will not be needed.
Introduction to Genetic Analysis, 9th Ed. (Griffiths et al., 2007)
This will be widely available locally, as it's used by BIOL 334. The previous edition would be fine too.Modern Genetic Analyses, 2nd Ed (Griffiths et al. 2002)
This book's approach to genetics comes closest to that of BIOL 234. It may be available locally, and is very cheap through Amazon. Unfortunately there isn't a newer edition.Genetics: analysis of genes and genomes (Hartl and Jones 2008)
Concepts of Genetics (Klug et al. 2008)
Essentials of Genetics (Klug et al. 2009)
Genetics: a conceptual approach (Pierce 2004)
The books below are not suitable as your sole textbook, though you might find them helpful or at least entertaining:
The Cartoon Guide to Genetics (Gonick 1991)
Genetics for Dummies 2nd Ed. (Robinson 2010)