I did not see where you saw the$100, down, but I will tell you what it may be.
A HUD owned home. Go to http://www.bidselect.com and put in the information for this are and see if it comes up.If you are purchasing a HUD owned home for yourself and bid the full price there is an FHA loan available just for that. I am a HD agent but not in your area, on the site you can find HUD agents in your area.
I offer fast responsive services and not only are my services free to you but i also rebate 20% of my commission after closing.
thanks for your time and dont hesitate to call or email me