Is it illegal to sell a woodland military flak jacket?

I'm a former Marine and right around the time I was getting out and turning in my gear I found out that I had an extra woodland flak jacket. Don't ask me how that happened because all I can say is that Marines leave their stuff all over the place and I tried to find out who it actually belongs to but nobody came up so I kept it and I never turned it in because well... I thought maybe I can sell it on the outside once I'm out of the Marines and make a couple of extra bucks for it. However I was wondering if it's illegal to do sell one in the civilian world? What would be the consequences if it were Illegal? If not, then how much could I get out of it?