Please folks do not forget, that 95% of us do not have the tank size required to keep a gigas as it matures. It is not the same as a piece of coral, that can be propagated.
I would hate to think of someone buying one of these creatures keeping it for a few years and then realizing that they have to get rid of it, because they cannot support it. These guys get very large and unless you have a super duper sized reef, I would suggest passing on these mollusks.
Best of luck all.