Yeah, they are expensive. My dad ended up getting the set they had from when he was a kid, so I grew up with some of the older lionel stuff from the late 40's or 50's. It was kind of one of the things that he did with my sister and I when we were kids. He dedicated half a garage to it. We built mountains out of plaster of paris and screen. Had slot cars that were integrated, and two trains running on different loops. My dad was the bomb. My sister still has all the old trains, just in a display case until she has a place she can realistically set it up.
An N guage setup the size of a door can get intense...those little things are so detailed and have so many accessories you can do a lot with them.