you can get the vases at Dollar Tree, 3 bags of rocks and the floating candles in a 6 pack at Hob Lob. With a super gorgeous orchid as the flower, in the colors of the wedding, you've got yourself a very pretty, and very thrifty centerpiece!
Buy rectangular vases, fake flowers, rocks, ribbon, and candles the width of the rectangle. Glue the flowers to the rocks and fill with water. Float the candle up top. Glue the ribbon around the top of the vase.