All good advice I would also look into what maay be done to keep an intruder out. Sense you are on a budget there may be ways to safeguard your loved ones and yourself. Like making it a layered type defense.

First as difficult to get in as you can make it.
Second if break in is occuring then a cheap motion alarm to alert you.
Third a safety plan to get everyone to the safest place.
Fourth whatever method of defense you have chosen for your protection.

A old coke bottle could be easily balanced on a door knob but would fall at the lightest touch.

Thin string with bells can be strung across windows.

There are probably lots of common sense, cost effective things you could do.

Hope this helps.