Just wanted to give an update...
I called about this service, and you can order the service now, and cancel by September 20th for a FULL Refund (i.e. get to watch week 1 and week 2 for free). This is true even if you don't DTV. After that, there is NO refund, and you still have to pay the full price.
He said about mid season, they do offer the sunday ticket at half price.
Please, call to verify it yourself because sometimes CSRs talk out their ***.
So potentially, you can order now and cancel on September 20th, then have another person order it midway through the season. You'll miss Week 3-8ish, so just see if it is worth it. I couldn't get a discount on the full price.