Question about security door/ window grills

[Yazmin]

I know these look ugly but my security is more important. Just been shopping around for some quotes and there are significant differences in price. 1 firm told me his products never rust and the other states all metal eventually rusts and both companies use powder coating.

Can anybody tell me is it worth the extra money and quality does matter in this instance or should I just go for the cheaper option. Both have the 5 lever locks..

I'm confused????? Does anybody know anything more ???