Hello and Welcome to Justanswer,
These links have of many online stores that sells educational posters and props that can be used in a classroom:
Most of the above stores have stickers, Postes games and props used in a classroom setting.
I hope this is helpful. If this is not what you are looking for, please let me know and I will try to locate other items for you. Joan
These posters from the links can be used on the walls of the store as decoration. As that have about reading, mathmatics and science.
What you also may want to do is contact some of the bigger educational companies that may toys and materials like Hooked on Phonics or Leapfrog or Mattel for promotional materials for the store. That all have materials and PR packages that that they will send out to see if they can interest you in selling their products.
Another big company is Scholastic, who usues Clifford the Big Red Dog. You may even be carrying some of the companie's products. Joan