If there are any government salvage facilities nearby check them out for a safe. I bought five large Mosler safes (had to buy the entire lot) at a government salvage sale several years ago, the safes are 1475 pounds empty, they are five feet high, 42 inches deep and thirty inches wide. The only bad thing, the door is on the thirty inch side, usually when I want something it is in the back of the safe and I must unload it to get to what I want. The safes were military police gun safes and set up for ARs, just a little modification and they serve my needs very well.
I paid $1250 for the lot, picked out the two best looking safes then put the others in a garage sale for $550. each. They sold within the first hour, I got my two safes for NOTHING, and put four hundred in my pocket for my effort.
Don’t overlook this source, the safes I bought were in excellent shape, they are top-of-the-line safes, fireproof and meet Milspec specification for security. Keep in mind, ANY safe can be breeched, the important thing here is how long does it take for a burglar to breech the safe?