I just wanted to add my opinion. I got married on 6/7/08.
Wedding dress sizes DO NOT correlate with your pant sizes. Believe me.
I had seen a dress and tried it on in the store that I LOVED. However, it was not in my price range. I was surfing Ebay one day and found it! I ordered my dress off of Ebay. It a brand new Alfred Angelo dress that had been ordered at a boutique and the bride never came for it. I got a $900 dress for $265 including shipping. IT HAD NEVER EVEN BEEN TRIED ON!!! I was between a 20-22 the dress on the net was a 26. It came and I tried it on. It was a little big. This happened last August.
May came and I had lost 42lbs and the dress completely hung off of me. It was wayyyyy too big. So I went to the local seamstress she took a total of about 15 in out of the dress and it cost me about $60. However, I do live in a small town and I think I got a deal on the alterations.
So my advice to you is buy it to fit you now. You can always go smaller but very rarely can you go bigger. It also feels nice when they have to cut 15 inches out of a dress because of the hard work you have done!
Also, check the fashion bug and target websites. I discovered during my planning that they have GORGEOUS dresses for less than $200. Just search for "Bridal".
Hope I've helped!