I'll second the recommendation for Warrent Trafton, he is a very knowledgeable and agreeable guy. And I bet there are as many boats in the few miles of RI than in the two hundred miles of CT. Plus I would expect Warren to have a good handle as to what is available in CT and in MA.
Another issue for buying a boat in CT is to have a plan to avoid the 6% sales/use tax. If you buy a boat through a CT broker, and its in CT, he may be required to collect the tax at closing, which you can then try to get back...the nice thing about RI is no sales/'use tax to work on evading...
PS, if you plan to keep the boat in any state except RI for 90-180 days, you may need to pay that state's sales/use tax...something you don't want to have to do!