This might be a good time to get to know the shop's owner(s) and/or employees better.

Do they smoke? If so is it cigarettes, cigars, a pipe, or something else? Do they use a smokeless tobacco? If so is it chewing tobacco or snuff? Do they drink? If so what's their favorite? Is it beer, whiskey, bourbon, etc? Do they shoot? If so what's their favorite gun and caliber?

Point is, find something they like or might need and if possible keep some around to barter with. It might also be something you'd like to have or need which doubles it's usefulness.