Sportsmens Steel Safe (Long Beach/Compton, CA??) has some of the less expensive models and they are fire rated....by them.
Some folks say fire rating (I suppose nothing is fire proof) a gun safe dictates that you have fireproofing stuff (ceramic maybe???) on all sides, roof, floor and door. My Sportsmans safe has it only in the sides, not the door. I suggest you make sure the safe has a UL listing regarding the fire rating, not just what the maker/vendor says.
This company:
http://www.hallsafe.com/ makes some of the best safes around, IMHO.
If you buy a used one, make sure to check out that particular model on the company website regarding the fire rating. Maybe the seller even has the paperwork from it and you can read the UL listing from there.
One thing to look for is air gaps when the door is shut. If there are air gaps (door rattles), there will be gaps for fire/heat to get in also.