alarms and hostages
Sheesh, what a title. I'll have nightmares from my own post!
As for alarms, go to Radio Shack. You will not be able to get a monitored alarm unless your landlord springs for the bucks (and if you're in a complex, that is unlikely, although if you're renting a single family dwelling you might be able to negotiate something). Radio Shack has all kinds of alarms that you can use for a rental situation, including magnetic alarms that will go off if somebody raises a window; motion sensors which, theoretically at least, can be set so that small fry and the dog won't set them off but an intruder will. Go have fun on Saturday and poke around and see if you can't find some stuff that won't be too much money but will increase your security.
Hostage: well, if anyone were to get to the point of holding my kid hostage it would be because he'd already climbed over my dead body and pile of brass to get to him (if I was home). Youngest Son is 17, though, and does sometimes stay home alone, obviously (can you imagine if I tried to get him to accept a baby sitter? only if she looked like Pamela Anderson, LOL) and he has some training from us on what to do if somebody busts in. The operative word is: RUN. He can't even have access legally to our shotguns if we're not home until he's 18, so he has all these swords, knives, etc., (Ninja Boy) but he has been taught to bail out of his window and run to a neighbor's if there's trouble. If the constable across the street is home, that's the best option, obviously.
Your kids, young as they are, can be taught to run to a safe place: the oldest ones are in charge of the younger, whether they have to carry them or whatever. Make arrangements with a neighbor. If you all are on the first floor, they can get out their windows and outside. If you're in an apartment complex or on a second or third floor, you need to make escape arrangements in case of fire as well as your hostage concern. If you're off the first floor, you should have those escape ladders (dk who sells them, but I'll bet your local fire department could tell you) so your kids could escape away from fire if they can't walk through your house. At any rate, the same sort of ladder arrangement can be used to get your kids out in case of a home invasion.
You want to have as many options as possible to get them out safely so there is no chance of a hostage situation occurring. I think that is the key here. ONce your kids are hostage, you had better have the professionals there to negotiate and get them out, because you are probably going to be unglued and NOT be the person to accomplish it. But that's just thinking about how I would be, maybe.
Hope that helps. Do everything on this earth you can to keep it from happening, give them options and train them how to use them, and then you've done all you can.
Springmom