Where can I get materials to install a home fire sprinkler system myself? I will begin construction of a new home next year, and I would like to put in a sprinkler system while the walls are open. Are there any resources that will help me calculate the correct number and placement of the sprinkler heads?

These generally are available to contractors only but you can try contacting plumbing houses in your area. The placement of the heads is dictated by the types of heads and the area they disperse water.