Got mine at davids bridal for $650! I added the belt, which was $150, and then alterations were $400... I was surprised at how much those were! If you get one that doesn't need a lot of altering you should be fine! (Taken at alterations so disregard all the pins!)
Davids bridal, trunk show, sale rack, sample sale, no budget is too small! My aunt got my cousin a $6000 dress for $800 at a sample sale in NYC so everything is possible
I got my dress for around $100 on sale at David's Bridal. Granted, mine is a more casual style, but I think you can definitely find what you want for your budget there. I had another $65 in alterations.
I didn't buy that veil, because it cost as much as the dress.
I bought this dress online for less than 300, I got pretty lucky as it doesn't look or feel cheap. Miraculously it fits perfectly. It has a little stretch so It doesn't need alterations either.