If buying a $300+ dress is not currently in your budget you can still get the high street style that is afforded to the new Duchess of Cambridge. To sample Kate's fashion sense for yourself, the new site http://www.labellease.com/ has just the offer for you.
You can rent a Reiss Shoala Dress for either 3 nights (£69), 5 (£79) or even a full week (£89). The site allows you to rent up to two dresses at the same time.
Label Lease is offering a 15% discount to new customers using code LLWelcome.