I would recommend that everyone get trash the dress photos! We paid $600 for a 1 hour session, but it was totally worth it. Our TTD pics turned out to be my favorite pics we got. It was really fun to do too. The experience is worth it! Now we have pictures that are beautiful enough to blow up as pieces of art too!
As for the dress, I got a polyester dress from Davids Bridal in their $99 sale. The only real similarity to my actual dress was the sweetheart neckline. It was perfect though! The polyester didn't absorb water which made it easy to work with. It also worked really well in the water and mad for pretty pics.
If you don't want to spend the extra money on a second dress, everyone says that their dress comes out fine after a good rinse. I was just too nervous to try that....
My two cents though.... Every bride deserves to get a beautiful set of pictures like this! TOTALLY WORTH IT!