As of this season (I believe) players have been getting $5,000 fines for flopping. I know Tony Allen got fined for flopping in the playoffs vs. the Spurs. (His flop caused Manu Ginobili to get a flagrant foul which directly led to the game going to overtime)
And I believe either Derek Fisher or Thabo Sefolosha got fined $5,000 when they both simultaneously flopped against Omer Asik.