If guitars are a little bit too pricey for your wallet, maybe you could try to learn to play an ukulele instead? Those are considerably smaller than guitars; they are more easily portable and fit into a dorm room well; and they can cost less than guitars.
You can get a new Epiphone Les Paul Acoustic/Electric ukulele at [ame="http://www.amazon.com/Epiphone-EULPHSNH1-Acoustic-Electric-Heritage/dp/B0053CUHMG/ref=sr_1_2?s=musical-instruments&ie=UTF8&qid=1321189694&sr=1-2"]Amazon[/ame] for $99. (The one listed there is an Alto, or "concert," sized ukulele, about 24 inches long, with laminated maple top. Beginners beware: that model doesn't have perfect intonation up the neck, and could stand to have a luthier do a setup service on it.)
You don't get the trapezoidal Gibson fret markers on that one; but Gibson does own Epiphone, so it's a genuine Les Paul.
Search Amazon or eBay for Fender ukulele: they have three different grades of the larger Tenor size, about 27 inches long, from $149 (laminated top) to $300 (solid mahogany top); but Fender also has an acoustic (only) Alto for $100.
Dozens of brands are available; tiny shops such as Mya-Moe have waiting lists, and have only made maybe 500-600 instruments ever; but Kamaka in Honolulu has been at it for nearly 100 years. Martins are the gold standard of production ukuleles, and used ones are still out there. Martin did quit making ukuleles for a while; but they have started again at a factory in Mexico (I think).
There is also a 100-year history of used instruments that frequently become available.