I'm not aware of one particular store or site where you can purchase Lab related items. We have had labs for over 25 years and we have collected quite a few items. We have plates from Killen, reproduction tin signs from shotgun shell manufactures,various throws and hangings,beer steins, brass lab hooks, the list goes on.
A good start might be with the large outdoor retailers ,Gander mnt.or Bass pro shops. LL bean has stuff from time to time. We just keep our eyes open and pick up little things here and there.