Have you tried hotwire.com? We have always had excellent luck with them. Last month we got the Radisson Orlando/Celebration for $51 a night, and the Hilton Atlanta Conference center for $53 a night. Both hotels were listed on their websites for well over $150 a night.
As long as you book the correct area you want, and stay at 3 stars or more, you can end up with a great hotel for an even greater price. I would at least check it out, it can't hurt and it doesn't cost you anything.
The only caveats are, you don't find out the exact hotel until right after you pay, and it has to be paid in full right away. It is usually pretty easy to figure out the hotel first though if you look at the amenities and the area on other websites such as tripadvisor.com.