Places (other than the college bookstore) you've used to purchase textbooks.

[Prloko]

17 U.S.C. § 107 : US Code - Section 107: Limitations on exclusive rights: Fair use
Notwithstanding the provisions of sections 106 and 106A, the fair use of a copyrighted work, including such use by reproduction in copies or phonorecords or by any other means specified by that section, for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research, is not an infringement of copyright. In determining whether the use made of a work in any particular case is a fair use the factors to be considered shall include - (1) the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes; (2) the nature of the copyrighted work; (3) the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and (4) the effect of the use upon the potential market for or value of the copyrighted work. The fact that a work is unpublished shall not itself bar a finding of fair use if such finding is made upon consideration of all the above factors.

I've discussed this with the local Librarian, who at one point allowed me to make copies of the glossary pages of a textbook, along with copies of the pages listing changes in the most recent text from the previous edition.

It seems to me that as students [scholars], since we are not looking to earn credits for a single course in order to financially profit, fair use would include PDF reproductions of textbooks.

factor (3) and (4) is the important distinction. An entire work reproduced is NOT fair use, but copyright infringment. Fair use alludes to quoting paragraphs or reproducing sections for criticism. For example, on youtube, you can legally provide a clip of a movie for fair use if it involves critique, reporting, etc. You CANNOT, provide the WHOLE movie for the purpose of critique.

Either way, I've downloaded PDF texts before, especially when the book wouldve cost over $200. They are more difficult to find nowadays, and as stated earlier, you're opening yourself up to viruses.