Other options would be Norwood (
OWD) to the south and Beverly (
BVY) to the north, both of which are near I-95 and Rte. 128. Both appear to have nearby MBTA commuter rail stations as well;
North Beverly is two miles from BVY and
Canton Junction is less than 3 miles from OWD.
I've never done what you're doing so I can't make any personal recommendations, but I would imagine that those two might be cheaper than BED. According to AirNav, 100LL is $7.03-$7.14 at BED, $5.98 at BVY, and $5.75 at OWD.
You're best bet would be to read reviews on AirNav or AOPA's online directory, call all three FBO's and inquire about fees/costs and transportation, and check out
www.MBTA.com.