I got one last weekend at a garage sale for $20.00. It is in really good shape and even came with a battery recharger.
Check out the classified ads in your local paper (hardcopy or via the internet).
In the past, I bought my DD a name brand light up doll house complete with furniture in the summer at a garage sale. I keep it hidden until Christmas.
At our house, Santa leaves the big gifts under the tree - unwrapped. This is great because many of the books (Twas the Night Before Christmas) and shows (The Grinch, Rudolph) show Santa leaving unwrapped presents under the tree.
Santa doesn't have to use wrapping paper and it is so much fun to see the kids' reactions to the gifts immediately. Also, the toys are all set up and ready to be played - without having to take time to get the gifts cut out of the box, batteries installed, etc.