I just ran into this with a blue-ray player. They have a 30 day limit for a price adjustment. As it turns out, my player was a Christmas gift so it was still new in the box. I was able to return it and rebuy another one.
The woman at the counter did tell me if they didn't have anymore on the floor I could rebuy the one I was returning. She even checked to see if there any on the floor before I walked away.
Sadly, I think (based on my experienec) if you can't return your TV because you have already used it, you would not be able to get the price adjustment.