That combo is an exclusive through one distributor, but I don't recall which one. There is always the option of buying a FS, then getting the compact grip module and magazines separately. It probably isn't difficult to sell the FS grip module (a lot of folks like to experiment with them) and magazines, if you won't need them.
take a look at gunwatcher.com using: sig p320 compact
Gun Free Zones Aren’t an Inhibition….they’re an Invitation.
Slickguns.com too