danawa had an easy link system to used electronics before their site redesign. now it is accessible from the top menu i think the second link from the left... but i am not sure.
just follow mp3 and cowon (고원) and roll. lately i have seen no old d2s... last year, there were a few up on that site each month.
mine was working, so i tracked them.
i actually went to a d3 (used, that site) after i dropped my d2 and also ruined the sd card. got a fantastic deal on this unit and, though i honestly liked the old d2 better (size was perfect for my needs, plus such a rockboxable powerful amp, and cheap memory, with the best battery life ever, and parts are cheap!).
the d3 is... ok. also rockboxed, but not so convenient. hardware buttons are, well, sometimes useful. otherwise slow and buggy side-apps. still a very good sound and drives the budget superlux phones w/o a hitch. battery life is a failure, however, and this is ultimately my deal-breaker...
people, here, get these things for gifts, and then listen to music with their fones, so they sit in drawers, in closets, in original boxes, and forgotten - get tossed. too bad.
keep on eye on danawa - the used site is green in trim, the retail is blue...