I'm 35 miles out of Boston but here's a list of Boston area shops.
I haven't been to any of these but Google is your friend.
Beyond Vape - Somerville, MA
Cumulus Vapors - Melrose, MA
Eastern Vapor - Brighton, MA & East Boston, MA
Essex Vapor - Saugus, MA
MassVapors - Allston, Beverley & Lynn, MA
New England Vaping Company - Watertown, MA
Vape Daddy’s - Newton & Framingham, MA
The Vape Shop - Brighton, MA
Vaper-US - Malden & Everett, MA
Vapors Guild - Peabody, MA
Vaporvana - Wellesley Hills, MA
Allston/Brighton is close to Back Bay