It won't be 9mm, but Sig has a .22 conversion kit. It won't have the same bang, but it will be cheaper and easier to get.
As far as 9mm, my carry gun is a .40 XD sub comp. and if I get a 9mm barrel and mags or a .357 Sig barrel, I can shoot those as well.
Just an aside, but the Sigs and the Glocks; talk about your beauties and beasts, but I digress. Hope you find some ammo to sling downrange.