I found some grade 3 with very good reviews for about $9 a piece. I'm not the prepper type where everything needs to be 100% waterproof i just need somewhere secure, dry and durable to store ammo. Is grade 3 okay or should i shoot for grade 2? Also, what price's are good for these cans? Gun shows around me are more AR and pistol crowds and the days of the military surplus are gone.