Although it's certainly possible to buy packaged crepes at most of the supermarkets in the Cambridge area, the larger question looming in my mind is...why? They've always struck me as something of a less tasty mid-point between from-scratch and from-the-creperie.
On one hand, you've got La Creperie (fka Arrow Street) a few blocks down from Inman in Harvard Square, that will certainly deliver your Nutella and banana for a buck or two more than a package of crepes.
On the other hand, if you can make a pancake from scratch, you can make a crepe from scratch (just add a little more egg and milk). If you were hosting a frenetic brunch party for 30, I could certainly see the appeal of a few time-savers, but if you're simply satisfying a craving (and are headed to the store anyway), make the crepe batter yourself, then revel in your genius in the kitchen!