A safe is absolutely worth it. But buy right or buy twice should be your thinking.
We've got a local guy that builds the best safes i've ever seen on the market. Large variety in size and configuration. He even delivers them. his hinges are interior and his fire protection is the best i've seen.
You should definitely do your research on fire protection though, if that's an issue for you. I've found that most of the readily available safes (like the ones you'd find at Walmart or sporting goods stores) can be hit or miss when it comes to adequate fire protection. Check out the web page below for some info on how to pick a safe that's right for you. You'll have to scroll down some distance to get to the section on fire resistance, but it's worth the effort.
How to pick a gun safe
Basically, the thing to watch out for is the maximum temperature reached inside the safe during tests. Most companies will give you an average, which is low enough to protect most things stored in the safe. But if one area of the safe reaches a higher temperature say 400 degree F you might lose whatever is in that area, especially if you plan on keeping documents in your safe.
One other thing: always, always, always buy a safe that can accomodate at least 1.5 time the number of firearms you currently own. Save you the hassle of trying to get them to all fit as your collection grows. Of course, you can just buy one for the most valuable to you. If that's the case, then ignore this bit of advice. But if you plan on protecting them all, buy bigger than you need. You'll find eventually you'll run out of space even in that.