If you are handy with a screwdriver, understand directions, and can put batteries in they have completly wireless systems you can purchase online. You can purchase a manual to determine if you want sensors on the windows and doors or would rather use motion detectors in the most vunerable areas.
The systems today can also incorporate fire detection. Do a google search and you might find it is easy enough for you to install.
I suggest that you try Edwin Nunez; cell 310-0526; email@example.com. He installed a wireless system in our POP home recently; I was well satisfied. He speaks good English; gave a written price in advance, & showed up on time!! Some minor problems? He returned twice to fine tune the system. He also wired my POP dentist's office. Do it myself? No thank you. There's a lot of measuring, cutting & drilling. Plus, . . the stakes are simply too high. If your self installed system fails, . . . .? I think that he works in Santiago. Good fortune.