The cheapest way I know is not to have them get their texts from gutenberg.org. When I teach intro courses and am responsible for selecting the material, I do not use any texts that cannot be found free on that site or elsewhere on the internet. I even have some texts that I have downloaded from the internet that I place on BB. This does not violate any copy-write laws as this material is now in the public domain.
I am dumber then a bag of dirt. The 1st sentence of my last comment should not contain the word 'not.' Have students get their texts from that site. IT is free:)
For those who don't know about it, Jonathan Bennett's www.earlymoderntexts.com provides Bennett's "translations" of early modern philosophical works for free. Bennett renders everything from Hobbes and Hume to Kant and Rousseau in contemporary English, without simplifying the philosophical content. (See his explanation here.)
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