I may have to take a closer look at the SIG...I didn't check the price tags, but the Beretta and Glock were around $500 - $600.
Is the SIG much more expensive?
Many believe a good place to start with handguns is a good revolver - either a .357 or .38 special, depending on whether you plan on CCW or not. Also, considering that you already own a .44 mag rifle, you could consider a .44 mag revolver and shoot the same ammo. Kinda hard to conceal one in a big ol' N-Frame, but it might fit right in for you otherwise. Might have to download it a bit for personal defense. Just a thought...
Again, do what you want, be safe, and take a friend shooting. (Lots of these gun choices get down really to what you like best, if you hadn't already figured that out.)