We bought some at the concierge at Pop in January for my nephew's birthday. When I asked the CM, his eyes kinda got wide and he said something like, "Wow, I haven't had anyone ask about those in a long time!" He asked a few people and went in back and found some. He said that they were on the way out and he didn't know how much longer they would be available. They were the 2009 ones, which makes sense since disneydollars.net says they haven't released 2010 or 2011 sets. They're pushing the gift card now... Disney dollars are going the way of the phone line modem and the floppy disk.
My advice if the Yacht Club concierge doesn't have any: try the Beach Club, try Boardwalk, etc.
***Also, since we are moving towards a cashless society, I feel I should mention that you can only do a cash-for-cash trade for Disney dollars. No charging your Disney dollars.