The Probability and Improbability of Loaded Dice in Manhattan

Several weeks ago I tried to buy loaded dice -- to illustrate some principles of probability for some of my students. The people at the gaming store that I found, however, said they had no loaded dice and did not know where I might procure some. One employee did say that loaded dice (with magnets) are expensive, perhaps $800/a pair. But he promptly added that it is impossible to buy loaded dice in Manhattan and that he could not tell me where I might buy some.