Deven, you've struck a nerve!!
My Portuguese Mom grew up in Cambridge but could never find linguica after she moved to NYC. I remember as a kid, whenever we went to visit my grandmother or one of my uncles, or they came here, there was great exchanging of linguica and at least one breakfast of linguica and eggs. They'd chop it into 1/2 inch cubes and fry it for what seemed like an endless amount of time and then add some eggs and scramble the whole mess. When it was done the eggs were light orange from the spices in the rendered linguica fat. You could smell it all over the house...
As I grew up, those trips became less frequent and I determined to find linguica in Manhattan, City of Plenty. I actually found two different places (one was a restaurant on 46th St. that Mom would call a few days before she wanted her linguica fix and they'd order extra for her to pick up), but alas those sources have dried up. I now have no Manhattan sources.
However, as mentioned here, there are Portuguese communities in Mineola, LI, Newark, NJ and Ossining, NY. I'm sure there are others (I've noticed Portuguese restaurants in Danbury CT for instance). Since neither Mom nor I have a car, I have resorted to the magic of the web.
Our current solution is to order from Sardinha's, located in Fall River, MA. The url is below, although you can order by phone or (how quaint) mail. I believe they have a minimum order, but it freezes well (it wouldn't feel like home without some linguica lurking at the back of the freezer waiting for a visit from Mom or Bro!) We've (my mom, brother and I) tried several of their products and, oddly enough, the one that immediately brings me back to those childhood feasts are the linguica franks.
FWIW, on a trip to Cambridge, I brought home some Gaspar's linguica (as suggested in Bilmo's post), and found it had some gristle. We prefer Sardinha's.
Hope this helps. And please, let me know if you find a Manhattan source.
Deven--Ossining has a large Portuguese population. I'm absolutely positive you'll find 'em there. Hunt around!
The restaurant formerly known as Lisboa a Noite (which I didn't love but Zagat did) is presently a mex/portuguese hybrid, and they use awesome good chorizo (La Puerta 107-109 Main Street 914-941-4479), for what it's worth.
Also, you can read my review of that place, btw, on Slate.com, via the link below (it was my wednesday entry in a week long diary there)