There aren't really any cheap hotels convenient to the ../StataCenter. The three closest non-cheap ($200-$300) hotels, all within about a two minute walk of the summit are:
MIT has a page of some other hotels near MIT, but they are also all expensive.
You could also try Expedia, you can find cheap hotel deals there, starting around 105$ a night in Boston.
Since the Stata Center is easily accessible by ../PublicTransportation, you could stay anywhere on the subway (especially the Red Line. If you find a good hotel deal but aren't sure how well-located it is, ask the Boston crowd on #gnome-hackers.
40 Berkeley is a nice hostel in the Back Bay area and reachable by subway. Shared bathrooms, but nice staff and good prices.