Barney's website, burgdorf goodman's website. bloomingdale's website.
net-a-porter.com
BCBG?
not sure how dressy it is
you might want to get a shawl to cover your shoulders. a clutch as well.
my best friend had the same problem. i took her to a vintage store in NYC, she got her dream dress for $ 350 and vintage shoes. she was so happy.