Center Piece

I would try a home improvement store such as Home Depot or Lowells before buying searching Target or KMart. You might find them cheaper, although the edges might not be beveled or finished in anyway...you could easily remedied this by glueing ribbon of the same width around the edge (if the edge is too thin, you could add foam board cut to the same shape until the width is suitable to be hidden by the ribbon).

Hi
Try Michaels or any store that carries craft supply