When you get back to port check out DRMO and see when they will have their next auction. I picked one up from my old bases DRMO for about 300 bucks that is mil spec and is fire and water resistant to mil standards, plus it came with an X09 lock worth a lot. If not I would also go with the winchester.
Also once you get it, don't foreget about a good dehumidifier to absorb the moisture. Check out
www.midwayusa.com for good dehumidifiers.