I thought I'd add because I rent an old victorian house, and the word budget is my middle name.
After a bunch of young vandals kept messing with my car, and eventually broke into our cars, An aquatance of mine who knows a thing or two about breaking into houses (yes he payed his debt to society) came over to help me evaluate my home security. I wasn't able to afford nearly the upgrades he suggested, but we were able to come up with some creative solutions.
At first I thought any would be robber would overlook my home. In its outward appearance it is rather delapidated, especially compared to the near mansions on our street. Of course my house would be overlooked.. not. My buddy said yes, they might have more or better loot, but my house is easy. Crooks always look for the path of least resistance, and it would be assumed I'd at least have a tv, a computer, the NRA stickers on my truck suggest I'm a gun owner, and what guy my age doesn't have some sort of gaming console. Well, I don't but I fit the demographic.
The first weak point he found was the basement windows. One was already broken, the others only had a single pane of glass. The basement door to the outside was as old as the house, and not secure at all, so we boarded them up with plywood and painted them to match the foundation.
The second was the huge front double doors. So I replaced the locks, jambs, and hinges. I moved the deadbolt down so that I couldn't be reached by breaking the door window.
Every other window in the house is single pane glass, and I can't afford to replace them, but I'm looking into the security film. In the meantime we put tack strips in the window sills, and planted thorny bushes underneath them. Security lighting now luminates every window as well.
My wife and I both work straight second shift, and my room mate works swing shift, which is good because it almost randomizes when the house is unoccupied, however there is a 4 hour window four days a week that no one is home. So we got a dog named dozer. A bullmastiff/german sheperd/great dane mix who is intimidating as hell. He barks and growls aggressively at anyone approaching the door, and barks laudly to alert us if something seems out of the ordinary. Once you meet him though, he is a wuss, and would lick you to death, but the crooks don't know that. A couple beware of dog signs add a nice touch.
A fake ADT sign in the yard might not do a whole lot of good, but its better than not having it at all, and Dollar store proximity alarms are now installed on every window and door as well.
When it was all said and done my buddy came back to re evaluated when we weren't home. He said that if he really wanted to get in, he could, but he would be far more likely to move on and look for easier targets. He also wasn't expecting the dog, and said that was his deciding factor for him not gaining entry.
Total cost :
new locks $60
Tack strips Had already
Security lighting $50
plywood free from work (came from used pallets)
proximity alarms $10
Thorny bushes Free (transplanted from hedgerow at my parents house)