The Renaissance London Heathrow Hotel (part of Marriott), located just 5 minutes from London’s Heathrow Airport, is currently selling rooms for just $91 (including taxes and fees).
The average rate for this hotel is about $200. Most of the rooms we found at this rate are for December 2015, but there might be more out there. The hotel fetches decent reviews on TripAdvisor and the newly refurbished rooms seem to be worth the money.
You can book this rate right at the Marriott.com website. If you do so, you will get stay credits and Marriott Rewards points for your stay.