What are your needs for hotel type ? Example: Hostelling International Boston - Chinatown has private 2 person rooms with double for about $130 per night.
http://bostonhostel.org/reservations/

There is also the Hotel Buckminster in Kenmore Sq that should be about $175 a night. It looks like they do not put out inventory this far in advance. I would recommend calling them and finding out when they release it. I have stayed here and it is nothing fancy, but the location is very good and clean. Everything is nearby including the T. http://bostonhotelbuckminster.com/

Here is what I would do:
1) Book a fully cancellable rate somewhere (best western)
2) In the spring 2013 look into airbnb.com and priceline for better more central lodging.

You may not be able to get a hotel on priceline until very late in the game because of the graduations and hotels holding them back but $175 should get it done at some point. You will have plenty of time to research zones/prices, etc.

Good luck.