This is a tough one. I'm a college student also, but live by myself so I don't have many of the concerns you have right now. Do you have an attic, basement or another room or closet that is not used much or is out of the way. Maybe you could store your guns there. The homak safe is a cost efficient way of protecting your guns, but is by no means burgler proof. However, it is enough to stop someone who might not have come prepare to break into a safe. Since you have housemates, probably the house is not left unattended for long periods of time, so this helps out. If your parents live in the same town, I suppose you could keep the majority of your guns there, and only keep the guns you use regularly with you at your residence. If you do find a place to keep a safe, make sure you find a way to disguise it.
One idea is to buy one of those 8 gun homak safes. Lay it down on its back, and build a frame out of wood or steel(depending on your skills) around it, with the sides of the frame closed off. Build the frame to the same dimensions as your mattress, and then use it as your base for your bed. The only way to get to your safe is by pulling off your mattress. This would keep your safe out of sight but would not allow fast easy access to your safe. If you use a box spring mattress under your regular mattress, then the frame would only have to support the outside of the mattress. Might have to get a lock box to hold your handgun, since you would need to get it out everyday.