Paper lanterns as light-up centerpieces--inexpensive idea. Slip a Vase in the middle of each lantern and add flowers of choice. OR just adhere silk flowers to top edge of lantern.Put BATTERY OPERATED CANDLES/lighting inside and around each lantern.
Coastal Wreath: Get a Grapevine Wreath or Twig Wreath from your local craft or floral store. Give it a nautical touch by hanging it off a rope, and decorate it with Beach Finds that reflect the season.