Population genetics on the cheap!

Textbooks are often very expensive. For example the most recent edition of Principles of Population Genetics will run you $50-$100. But it has come to my attention that the third edition of this textbook is potentially much cheaper, with some copies in the <$10 range! Population genetics isn't quite like math, where 19th century works are still interesting to the non-specialist (population genetics was 'invented' in the first decades of the 20th century!). But a lot of the older material is totally relevant and on point, so these previous editions are not just simply historical curiosities. Much of the third and fourth editions of this particular work overlap anyhow, the big difference obviously being genomic techniques and such. But for that you should probably read papers, many of which are thankfully being put out as preprints now. While I'm at it, I notice there are some affordable copies ($10-$20) of ...