One thing to remember about Boston Coach is they cater to businesses, and corporate accounts will pay a heck of a lot more than some of the smaller, independently owned places.
I've been using A Touch of Elegance out of Wakefield for my trips to the airport. I live about 12 miles from Logan, and it runs me about $65 plus tip one way for a towncar. The cost is 781-246-1648. They also offer limos, but I don't know what the pricing is. I have found that they are reliable, and the town cars are immaculate. The drivers are very friendly.
Are you renting a car when you go to Disney? Maybe you can arrange going in a limo from the airport to your resort. It will be a longer ride, and in my opinion, a much more special surprise than a 10 minute ride from the house to Logan. Just a thought