Dave, send Tim the size of your table in a drawing with dimensions and he'll calculate what you need and price it for you. When it comes time to expand, you can send him the whole size of the new table and an inventory of what you already have, and he'll package up the pieces you need to make the full configuration. I already had a bunch of the benchwork that I bought from a guy leaving the hobby, I sent my layout plot and an existing inventory and he came up with the stuff I needed to build the benchwork. He also sends detailed drawings and step by step plans to actually put it together, very slick packaging.
After I got started, I realized I wanted to move the lift-bridge that I included, and it was a piece of cake to simply bolt it together a different way and move it to it's new location.
The thing that took the longest was the lift bridge, and you do have to supply a couple extra pieces of your own material to put that together. However, it's super cool, and saves crawling under to get inside. 
