The SkiMarket chain runs several trips a week to just about every mountain in the New England area. THe trips originate in Conn, RI or Mass and are offered just about every day somewhere.
THese go for about $40.
Numerous ski shops in Mass and RI and NH also offer trips.
Red Hook brewery in Portsmouth NH offers a day trip to Wildcat for $20.
Some town recreation departments also offer bus day trips cheap but you have to call around. THe one I know of is Pawtucket , RI.
There are travel agencies which do ski bus trips, both 1 day and weekend. Theres one in my city which runs trips daily as well as European trips cheap. In fact they run a couple of trips to Stowe each season.
There's also a "Dine Out" style book available which has two for one coupons to the mountains. My buddy gets one of these every year and we go boarding, usually in the Berkshires, at half price.
I prefer to snowboard alone and these bus trips are the cheapest way for me to do it. For $20 to $40, I'm able to go at least once a week.
If it weren't such a long drive I'd get a season pass though.
RingW...
PS: There is a ski show held at the Exposition Center in Boston in October - I'll bet they hand out free passes to people who attend that show.