250,000 probably refers to the mintage of domestic "D" version Pandas... Small "D's" are likely to be very few in population.
Some do, some don't. The most commonly accepted history is that Pandas that were sold in 2001 for the domestic Chinese market were stamped/chopped with a "D" - while those sold overseas escaped the stamp/chop. In recent times, a lot of Pandas have been flying back to China - so there may be a lot of 2001 Pandas that don't have the chop.
Thanks, so what about recent year Pandas? I am currently in China, though leaving in a few days, would be cool if I could pick up a current year panda with a D mark on it. Though I have no idea where I could find a reputable dealer.