It does appear that the Sigma is no more. I am sure some dealer still carry it but sites like http://www.budsgunshop.com/catalog/a...6r6urf735e5cj6
are all out. The SD is basically the same pistol as the Sigma except for it has a better trigger (8 lbs) and a different slide and standard rail. Its $379 on the S&W web site so you should be able to pick one up at tuners for $329 to $350. Its the same gun. I would have to look at the sear assembly to tell you if I could make the trigger even lighter.