Do you mean whole house water softeners? Sears sells them, although you would want to have a plumber install it. You will also probably require some additional plumbing work to at least put an unsoftened cold line to the kitchen for drinking and possibly even a bypass for water used for irrigation.
http://www.sears.com/shc/s/s_10153_12605_Appliances_Water Softeners_Water Softeners?keyword=water softener&sLevel=2&prop17=water%20softeners
http://www.sears.com/shc/s/s_10153_12605_Appliances_Water Softeners_Water Softeners?keyword=water softener&sLevel=2&prop17=water%20softeners