I Wonder if it may be cheaper and better looking to secure your office and put the guns in a nice looking glass case.

Solid outside door, dead bolt(s), re-enforce the door frame, if first floor bars on the windows, etc. It doesn't have to be a safe room or bullet proof, just better. The benefit of this is you get to secure the whole office, not just the guns, and I assume you saying office translates to some paperwork you would rather keep a hold of and a computer or two as well as guns.

Then you could add one of these!