Hey man,
So yeah you got it right, Tremblant is a pretty expensive place to say the least - as a result I usually try to just go up for the day, but on a couple of occasions I have stayed a few nights up there.
Don't even bother looking into hotels in the village - you won't find anything below $150/$200 per night, even mid-week/off peak. Your best bet would be to stay at the hostel location in town (not the village) a couple of KM from the mountain. Their website is:
http://www.hostellingtremblant.com/2/home.hostel
For a private room it will be about $60 per night, but for a dorm style/shared room probably about $30 per night. By far the cheapest place i've found in Tremblant to stay.
If you have a car then perfect, you can just drive right to the mountain, if not then the town buses are fanstastic - the bus stops right across the street from the hostel and leaves all the time. When I have stayed up there I have taken the bus into town (dont drive) and made first lift).
The hostel is real nice, like a college dorm really. There is a bar (I think you get 1 free drink) and a common kitchen so bring some food (or there is a depanneur down the street) to make your own food. It's a great place, very clean, very quiet.
Enjoy Tremblant and message me if you have any other questions, need tips on where to ski/drink.
all.mountain