Are you just afraid of dumba$$ roommates doing something stupid with your guns? Do you want something you can get into easily? Or is something with a key or combo lock sufficient? There are hundreds of safes out there that have different uses. I have a couple safes. One is a large floor safe that stores almost all of my guns. It cost about three times your budget, but is meant to keep everyone out. It has a big combination on it and takes some time to access. I then have a
this Gunvault safe I keep very close to where I sleep (I can open it without getting out of bed) and mounted to make it hard to steal. SOmething like the gunvault might work for you, but I'd keep the backup keys at your parents house (to prevent roommates from finding them). I would also HIGHLY recommend mounting any safe you get, at least to a piece of furniture...but better would be to the floor.
Keep in mind that no safe is foolproof, and the less you pay, the easier they are to get into. The purpose of my small safe is to keep my 3 and half year old away from my loaded pistol. I would never trust it to keep a dedicated person from gaining access, so keep that in mind.
Your budget is enough to get something that will likely work, but again, depending on who you're trying to keep out, and how dedicated they are, it might not be enough.