Welcome! It's REALLY great to see a woman who is realistic about crime/violence and is willing to take a step toward protecting herself and her family. The guys have given great advice. As for a safe, my sister got me this for Christmas:
http://www.oneclickshooting.com/prodimages/78103.jpg
It's large enough to house a couple handguns, magazines, a bit of ammo, and money. It comes with two keys for the lock, but the main lock is programmed with four buttons. There are countless variable ways to program the keycode, and it's got the cutouts so you could easily punch in your specified code in the dark. You can operate it with a battery (lasts about a year), or plug it in. You can also mount it (it comes with a drilling template).
Trigger locks are dangerous. I don't want ANYTHING touching the trigger unless it's my own finger, which is all I have control over.
As far as keeping the gun out of the hands of your son, consider applying for a CCW permit. That way you can have the gun concealed on you at all times, and the likelihood of your son sneaking off your own body is pretty slim. Not to mention, if you don't feel safe in your neighborhood, if and when you ever need a handgun for defensive, it might not be in the home.
Good luck with your search for the right handgun. Also consider a 20-gauge Remington 870 to keep at home if you think home invasion is a possibility.
