Theodore Sturgeon's work was widely anthologized and reprinted during his lifetime. Copies of Sturgeon anthologies and sometimes the magazines where his stories were originally published can be found in many used book venues. Copies of some Sturgeon novels can be difficult to find: I, Libertine (under the name Frederick Ewing); The Player on the Other Side (as Ellery Queen); The Rare Breed (a novelization of a Western movie starring Jimmy Stewart); The King and Four Queens (a novelization of a Western starring Clark Gable); Voyage to the Bottom of the Sea (novelization of the TV show); and Godbody (published posthumously). Also of interest is James Gunn's novelization of a Sturgeon Star Trek teleplay, The Joy Machine. Otherwise, Sturgeon's work is available from the following publishers:
Vintage Press
Vintage Books issued all of Sturgeon's major novels; The Dreaming Jewels, More Than Human, Venus Plus X, and To Marry Medusa, plus a Selected Stories. They can be purchased from Random House.

North Atlantic Books
The Complete Stories, edited by Paul Williams and published by North Atlantic Books, collects 222 stories, including some that were unpublished. An index to The Complete Stories is printed in the last volume, Vol 13: Case and the Dreamer, published in 2010. That index can be found on this page. For more information about the volumes, including a table of contents, check our Complete Stories page.

The most recent volumes of the Complete Stories
Centipede Press
Centipede Press reprinted Sturgeon's 1961 horror novel Some of Your Blood, one of the most unusual vampire stories ever written. This 2006 edition also contains the story "Bright Segment."

Blackstone Audiobooks
Stefan Rudnicki of Blackstone Audio produced a dramatic reading of More Than Human (read by Rudnicki and Harlan Ellison®)
William Seabrook has one of the best Sturgeon bibliographies on the web, including covers of magazines and books. Eric Week's Theodore Sturgeon page contains other relevant bibliographic information, as does the Theodore Sturgeon Wikipedia page.