Have you ever been to Ward Maps on Mass Ave (near Porter Sq)? I recently saw that they sell prints of my favorite T map as seen above.
I'm not taking credit for someone else's success, but I feel a small twinge of pride since I encouraged the artist to sell reproductions after putting it on a Bostonist post and a CTB post.
There are some items in the store that sell for $10 or less, however I have eagerly spent more to but vintage maps of Boston and beyond. It's one of the coolest stores in the metro area.