Every town has a bunch of locksmiths. Call them all, telling them you want a big safe. The larger they are, the mire work they are to move. Very large safes are hard to sell for that reason.
Also call realestate brokers, because safes get left behind. Put an ad in Craig's list looking for a safe.
Anyone that walks into a box store ti buy a new gun safe has not figured out there is a less money option, that gets you more safe.
I paid 200 bucks for a huge two door UL rated jewelry safe. Another safe was 60 bucks, another was free.
You are not going to find a job box for one fifty. Used beat up one maybe.