Ouch! That rate hurts!!!
How important is it to you to stay at that particular Residence Inn? We stayed at a Residence Inn a few summers ago that is just outside Boston for about $119 a night. If I can remember the location I'll post it. I'm just having a senior moment, and the name escapes me just now. Anyway, I remember the continental breakfast was great, and they had fix-your-own waffles too! This Residence Inn was about a 20 min. drive to Boston, or somewhere thereabouts. We drove into Boston almost everyday, and even spent a day in Connecticut at Mystic seaport.
Sorry, I just don't know any codes for Marriott right now, but keep checking all the travel sites. You might want to give the hotel a call directly and ask if there are any special rates for the time you will be there.
Wish I could be of more help...
Just found the location --- it's Boston Westborough.