DIY signature cocktails. Obviously lemonade wouldn't make sense for Prohibition, but it's a cute setup. You could always do different punches. Plus, mixed drinks can be cheaper because you can use really low-end alcohol and nobody can tell the difference.
Wheelbarrow drink container (JoyandDelight.com): Make a wheelbarrow into a beverage holder; set drinks on top of ice; fun for a farm / barnyard party, garden birthday theme, John Deere theme, and more!