Best bet is E-Bay, but if you plan to fill that whole line-up, you better be prepared to fork out top dollar. 15lbers fetch premium prices. I just sold a used 15lb 3-D Pearl for almost $100 just to give you some ideal of what you might have to pay. My old 3-D High Rev, which was 16lb. still brought in $90.
Might want to ask user G_thing if he has anything for sale. He comes across the 3-D's quite often, although I don't quite know how where he'g getting them from.
Spike