I just want to mention, that Stack-On safe that stainless recommended can be easily opened by dropping a corner of it on the ground. There's a video floating around of a three year old opening a model similar to it, without a code, that uses the same locking mechanism. The safe looks all high tech and stuff on the outside, but it still locks with a mechanical mechanism. Defeat that, and you're in, without even bothering with the electronic part. Also, whacking it with a hammer is usually enough for the locking mechanism to disengage. So it's at risk even if you have it mounted. If you're OK with that, go for it. The Gunvault safe I linked doesn't have that problem, but it is about $50-60 (retail) more. Like I said before, the less you pay, the easier it is to defeat a safes lock.
That one I linked, of course, isn't fool proof either. I actually know how to get into it without a key or combo, but it takes more work. Will it keep your roomies out? Probably (unless they look up how to open them). Will it keep a determined thief from getting your gun? No way. For me, there are only guns in it when I go to sleep, so someone fiddling with it is going to wake me up. I just don't want my daughter coming into my room a 1am, opening the bedside table drawer, and getting access to a loaded weapon, so it works perfectly for me.
Good luck in your search for what will work for you.