It would seem to me that you could do cool stuff on your computer and print it out to make the art. If you know about this, drop me a line. The only limit is your imagination and ingenuity. Keep you eyes pealed for opportunity. Station Garage Sales may work.
Books are also a good item to sell.
There are also political and social organizations that produce material that can be purchased for wholesale prices and sold at information tables. This is a way to inform the public about wider social issues. These can be sticky if you station does not have a core political bent that is shared by all members. Invoke your own style of course. Service Swaps Selling things is not the only way to raise money, there is also selling services.