The nice thing about Edison cylinder phonographs is that most were -- or can be -- retrofitted to play the 2&4 minute cylinders--both wax and celluloid. Based on what I've listened to, the Amberolas generally do the best job playing the 4 minute Blue Amberol records, especially those with larger (internal) horns. About the only exception to this would be deluxe machines, such as the Edison Opera, etc., and of course, these are VERY expensive and hard to come by, today.
I'd advise that you do as much homework as possible prior to making any purchase. Then, to save yourself a lot of frustration, purchase a machine that has been fully restored, at least from a mechanical standpoint, from someone who knows what he is doing. You'll pay more, up-front, but probably save (in terms of money and the "frustration factor") in the long term.
If you haven't seen them, look over some of the Edison operator's manuals at
http://nipperhead.com/ephemera.htm
Other web based resources include --
Antique Edison Phonographs - A Beginner's Guide --
http://www.intertique.com/EdisonPhonographTutorial.html
Edison Reproducer Guide
http://www.edisonshop.com/en-us/pg_15.html
The History of the Edison Phonograph --
http://memory.loc.gov/ammem/edhtml/edcyldr.html
The Edison Phonographs --
http://www3.sympatico.ca/jean-paul.agna ... edison.htm