The good news is that the Big Bang Theory characters have been reproduced as minifigures by at least three different clone brands. Xinh has set X0125 which features two versions of Sheldon, Leonard, Raj, Penny, Amy, Howard and Bernadette.
Pogo has also made their own version of the bootleg minifigures, but only one of each of the characters. The set numbers range from PG-978 thru PG-984. But the entire set number is PG8025.