The Red color seen in cats is a gender linked color, carried on by the X gene. A male cat whose X gene is red will be a red tabby. A female who carries one red and one non-red X gene will be a patched tabby, a tortoiseshell, or a calico if she has the gene dominant for white. A female who is homozygous (meaning has both X genes) for red will be a red tabby. This is why there are more male red tabbies than females. This is why male calicos are so rare: you have to have two X genes to be a calico. While it is true that males are generally sterile, there have been documented cases of males that were not. Full documentation from vets and labs are needed before the sale of a functional male calico will even be considered "up for grabs." And the worth is in what the buyer wishes to pay.