InkEd;
You should always be careful about the construction of the unit you are buying. However, at your stated price point, you are almost certainly going to be buying an RSC, (Residential Security Container) rather than a true safe. There is no law in the U.S. that I'm aware of that regulates what may or may not be sold as a "safe". In other words I could tape six business cards together & put a bent pin across the corner of the "door" & sell it to you as a safe. The sad fact of the matter is that there is not a whole lot of protective difference among RSC's in your price range. Find one that has the features you need at the best price & buy it. Do check things like the thickness of the sheet metal in the construction, the size of the gap between the door and body (smaller is better), and who really made the lock. IMHO, things to avoid are internal hinges and cheap electronic locks.
As has been said, anything is better than nothing, do get something. And I'll second the suggestion to go to some locksmith's establishments around your area & see if you can't get a used true safe. Yeah, you probably will have to pay for delivery & installation, but the upgrade in security makes it money very well spent. True safes, U.L. rated as a safe, are heavier, sometimes a lot heavier, than an RSC. It's the difference between sheet metal & gypsum wallboard (insulation) versus plate steel and concrete.
900F