I'd be careful about buying a dress online. David's Bridal lists several dresses available with different colors online but when I went to the store they told me that the dress I wanted is discontinued and they don't manufacture it anymore! So imagine the hassle trying to order it online!
If you trust the website, I don't see why you couldn't order it online, but I would recommend you understand the return and exchange policy very well, order the dress WELL in advance to make sure it's there in time, and scope out alteration shops just in case.
I hope that helps.

I really like the Ginger!