Or check the local Barnes & Noble. The one in my small town at least has "Nature" in the magazine section, at around $20/copy (but of course you can read it while standing in the magazine section...).
At first I thought "this can't be the well known peer reviewed journal!?", but it was full of full research papers and sure appeared to be a peer reviewed journal. I don't know if it is the exact same edition as universities get, or some special edition aimed at members of the general public who happen to like reading research papers. It did have a section in front full of general science news and articles, and the part with the papers didn't seem to have a table of contents which struck me as odd.
This wouldn't be the first unexpected thing I have found at a "normal" bookstore. At either a small Waldon's or B. Dalton's in a mall I found a copy of Misner, Thorne, and Wheeler's tome "Gravitation".