hmmm, i would likely divide and conquer...
any friends or acquaintances w/bigger vans (like the 8 /10 /14 passenger variety)? if so, offer them a few bucks for gas and their time to take you (dh helps friends w/this all the time!) and that would get half the group there...
anyone have a relative that lives somewhat closer to the airport who would not mind an extra car in their driveway? if so, park it and call a cab from their place (or offer them a few bucks to take you)...
how 'bout instead of a limo you order a "party bus" that holds more people/more luggage?
also, you might want to check in to park/sleep/fly and stay at a hotel the night before and let them transport you to the airport, leaving your car in the hotel lot the whole time... this worked GREAT for us... parking would have been $100+ but the hotel room was only $60! it also assures that the slow-movers are ready/packed/and nearby the night before!
yet another option would be to rent a car (or a 14 pax van) locally for a one day/one way rental and drop it off at the airport... do the same in reverse upon returning...
last but not least is an off-site parking lot like
www.avistar.com where parking might be cheaper than logan's on-site...
oh, and since you're in NH, have you looked into flying out of manchester instead of logan (i realize NH is a BIG state and you might be much closer to logan) 'cause typically fares are cheaper (via southwest) as are parking fees...
whatever you decide, good luck and enjoy
