Window bars?

Question:I want to install window rails in my high-rise apt.
Problem is, I know I'll have to pay for "damage" (i.e. holes from screws). Are there any window guard products on the market (or something I could make myself) that require little installation--i.e. maybe they're secured by suction cups or pressure (like shower curtain rods). The windows are huge (whole wall) and open side-to-side.
Thanks!

Answers:
Don't worry about the screw holes you can fill them with poly fil when you remove the bars. isn't peace of mind worth more than holes?