The below are mostly Schirmer editions, with some Kalmus, Salabert, Ricordi mixed in. These are OK for fun and are a good value. . . unless you are a serious student and must therefore use an authoritative score. Schirmer, Kalmus, Dover, etc. have always been a great source of Art music for the budget conscious, but for Chopin it becomes exceedingly important to use a true Urtext.
The most authoritative editons are published by G. Henle Verlag (Germany). Henle editions are expensive, but are editions that are well worth the investment. Any accomplished pianist knows the huge difference between 100 year old rescans of unknown sources and Henle Urtext. Henle represents the most recent scholarship in publishing Urtext editions, there are no inaccuracies in the score and no editor's opinions added (notes changed/added, pedal markings, changing Chopin's fingerings, etc.).
The Cortot editions are published by Salabert, and are listed below. Every pianist studying the major works of Chopin should have these editions in addition to an authoritative score. Cortot's insight and practice techniques are invaluable for overcoming the difficulties inherent in Chopin. I can't recommend the Cortot enough - your technique will improve exponentially if you master his technical drills.
Check out the below, but also take some time to visit the Henle web pages on this site.
Dr. Rein P. Vaga, D.M.A.
Sheet Music Online