.357 Sig worth the extra cost of ammunition?

In my opinion, which is what you asked, no. It is a round devised by Sig to get .357 magnum power out of a short frame pistol. With the 125 grain hollowpoints, it does just that. Even though it has been around since 1994, there doesn't seem to be much following as ammo is hard to come by and not cheap. The only advice that may be helpful is get out of New Jersey and move to a more gun-friendly place.