Wynton Marsalis. Maybe everyone doesn't appreciate his music, but nobody can fault his generosity. He easily offers the best marathon bargains available from iTunes, with eight songs of 15 minutes or more including the live 55-minute "In the Sweet Embrace of Life" and 40-minute "Citi Movement." Excellent stuff. Combine "Embrace" with his spoken introduction from the short tracks section and you have a full album for a buck.
Miles Davis. How about a few hours from the grand master of jazz for a few bucks? Several tracks exceeding 30 minutes each are available from his early '70s fusion period, with some other tracks such as "Sketches Of Spain: Concierto de Aranjuez" also available.
Branford Marsalis. Not quite as generous as his brother, but still better than most. A number of tracks exceeding 15 minutes, most of them live, are available.
"Bill Evans Piano Jazz" by Bill Evans. One-hour NPR show available as a single song from emusic.com as part of the Riverside boxed set.
Herbie Hancock. Several tracks, including some live compilations with Chick Corea.
Fela Kuti. This is actually world music filed under jazz for some reason, but with 10 tracks of 18 to 32 minutes available for a buck each we'll forgive whoever's responsible.
Lou Grassi. Three sections from his "ProGressions" clock in at a total of more than 57 minutes.
"The Real Thing (Remastered)" (18:56) by Taj Mahal.
"Concerto for Clarinet, Strings, Harp and Piano" (17:53) by Richard Stoltzman. Classical filed under jazz.
"Little Royal Suite" (20:20) and "E'S Flat, Ah's Flat Too" (17:07) by Charles Mingus.
Gerry Mulligan & The Dave Brubeck Trio: Live At The Berlin Philharmonie: New Orleans (16:01)
"An American In Paris" (18:29) and "Rhapsody In Blue" (16:29) by Leonard Bernstein and the New York Philharmonic.
"Concierto de Aranjuez" (19:16) by Jim Hall.
"Nomads" (17:21) by Keith Jarrett.
"School Days, Live At The Greek" (21:34)" by Stanley Clarke.
"The Lost Souls (Of Southern Louisiana)" (14:23) by The Dirty Dozen Brass Band.
"La création du Monde, Op. 81" (15:44). A "jazz in classical music" piece from NPR.
"Diminuendo in Blue" (14:19) by Duke Ellington.
"Avalon" (13:15) by Ella Fitzgerald.
"Honeysuckle Rose" (16:42) by Benny Goodman.
"New Orleans" (16:01) and Things Ain't What They Used to be (14:55) by The Dave Brubeck Trio.
The Main Attraction (19:35) by Grant Green.
"El Mar Mediterrani" (17:16) by Ryuichi Sakamoto.
"a La Carte" (20:48) by Joe Rosenberg.
Sixes and Sevens (15:26) by John Surman.
"It's Too Late" (16:23) by Johnny Hammond.
"Albert's Ladder" (16:35) and "Listen Tree" (15:25) by Ken Simon.
"Dream (Live)" (21:46) by the Mahavishnu Orchestra.
"Training" (17:28), "The Miracle (15:35) and "Spanish Key" (15:25) by Mark Isham.