I used X10 stuff with all my universal remotes for many years. It's very cheap and works ok, especially the lamp modules. Just pick up a cheap IR-543 on ebay for the IR interface. If you strike out, I have a ton of X10 stuff I no longer use, so just PM me. Also check out the Home Automation forum.
I'm not sure what x10 stuff is, I looked it up and it just says home automation. Theres no cheap IR-543 on ebay, I tried looking.
Will this work for just turning a lamp on and off via my harmony 900? http://www.smarthome.com/56225/Sylvania-SA-500-Wireless-Indoor-Plug-In-Remote-Control-System-1-000-Watts/p.aspx