See this link:
http://www.structuresusa.com/company.html
This company seems to have interesting products and that may be truly cost effective.
Thanks,
Tom in Portland, Oregon
If you want to experiment with a light weight concrete in non-code applications, here is a way to do it and get rid of that stack of newspapers in the corner also.
Glenn
http://www.northcoast.com/~tms/papercrete.html