I have always looked at it this way: Buy the best you can afford in the size you need. For some that might be a cheap $400 Stack-On 10-gun safe, for others it might be a $3,000 Browning 30+gun safe. As Rick said, anything is better than nothing and even a cheap safe will make a crook have to work a lot harder for his payday meaning more noise and more time on scene - both of which greatly increase their chances of getting caught in the act.