The word caviar evokes a luxurious and unattainable ingredient. Beluga caviar is particularly expensive because the beluga sturgeon is a threatened species due to overfishing. In fact, the United States Fish & Wildlife Service banned the importation of beluga meat, including caviar, in 2005, as the fish is on the U.S. Endangered Species List.
So, needless to say, if the recipe calls for beluga caviar, you're going to need to find a substitute, even if you can afford the real thing. It might not taste exactly the same, but in this instance, we suggest replacing it with a cheaper caviar, such as hackleback, keluga, ossetra or sevruga caviar. American-farmed caviar is another option. If you're worried about the dish having a lesser flavor because of the substitution, spruce it up with a little lemon juice.