Try this site
http://www.microtactix.com/
They sell through RPGNow and have a link to that site
This page has some for free but I don't know if the scale is good for what you want
http://www.alternaterealms.co.uk/free%20buildings.htm
This one has some pretty simple designs
http://www.germy.co.uk/paper25mm.html
This model railway site has some, this is the HO scale page
http://www.ontracks.co.uk/index.php?...talogue&cat=84