Well three things...
I highly recommend you save up for a proper safe, they're an excellent investment.
That said a good cheaper option that is also very handy is a tool cabinet like this. Now this particular one may not work if he has a lot of long guns, but you get the idea. They're lockable and when locked pretty hard to get into. Leave the wheels off and bolt it to the floor and it's near impossible to move. They of course organize well and provide a counter. Toss some water jugs in the bottom and they'd do OK in a fire as well.