I absolutely adore this dress Sarah Michelle Gellar wore on Aug. 20, 2009. The beautiful maxi dress is by Twelfth Street by Cynthia Vincent. The dress is hard to come by, but can occasionally be seen on Ebay & Poshmark.
Ebay Search Tip:
To find the dress, simply refine your search to the key words "Twelfth Street" in the dress section and refine your search to dresses with "spaghetti strap" sleeves and "not specified" sleeves.