There are offers for discounted rates at the following hotels on travelzoo.com :
Ocean Edge has discounts for mid-week stays through Sept. 7 and rates are available for $189-$199.
Chatham Bars Inn is offering discounts of $100 off of their rates. These rooms must be reserved by July 21.
The Beachside Hotel on Nantucket is also listed as offering discounted stays.
You can get all the information about these discounts here:
Enjoy the Cape!