you will love the 188c. i have it and it is great.
the chart you want is MUS003. You could also go with MUS501L which covers NH through NJ, or even MUS600SX which is ME through VA.
i had also heard that they had been discontinued, and i believe they are.
that being said, I see them on ebay every now an then.
Here is one:
http://cgi.ebay.com/GARMIN-BLUECHART...d=p3286.c0.m14