My personal choice is to purchase from the .cc (or adafruit) for new boards. YMMV. Craigslist locally of course has generic and .org boards now and then.
If I get a .org board on craigslist, will I need to use their fork of the IDE for the board to be recognized by the IDE?
My feeling is "yes" but I wanted to confirm.
A board there just now is Arduino mega 2560 from the .org. Would I have to use their flavor of the IDE?
Thank you for your thoughts- photo of the board I am considering is attached.