If you see a vintage tin sign in your travels, you should grab it quick; whether it's advertising for pop or other products, these are highly sought after to add bright colors to country decor.
Some of the most popular tin signs are those advertising soft drinks; Orange Crush, Coca Cola and many more that have faded into history are still around.
Look in garage sales, auctions and flea markets; be prepared to spend a lot on these, especially if they're in excellent shape. Many fell victim to bullets as people used them for target practice; these are still fun and interesting to display, but not worth the money that a pristine example would fetch.
Use as wall art under cover, because many of these signs won't withstand too much wear and tear; although designed originally to be displayed outdoors, some are just too fragile and precious to risk any more damage.