Specifically what types and formats of film would you be looking for? If you're using 35mm color neg and aren't picky about brand, it's not too hard to find a few rolls here and there. 35mm Tri-X and HP5 Plus are common at the camera stores that do continue to stock some film. Once you're looking for any less common emulsion, 120 or larger formats, or transparency film, the pickings get very slim, and you need to plan on going out of your way to find those few stores that still stock.
There is another option if you can plan a few days ahead - you could call Calumet and have them send to their Cambridge store whatever you will need, or call Hunt and have them send what you need to their Harvard Sq or Kenmore Sq location for pickup.