In the early Fifties there were Army/Navy stores everywhere, all sorts of surplus. I remember D-Day flotation devices for 75 cents, we all bought them for swimming. I bought an 81mm mortar shell and a training grenade for $1 each. The grenade was totally authentic, OD in color with yellow paint under the fuse (which had been fired). The body was empty of course and had a hole bored in the bottom.