Try this site: http://www.ehow.com/way_5485620_home-recipe-roach-killer.html
I've had these little plug in electric things, kills them in the walls; Used mine for over 30 yrs & never see roaches. I think Sears has them, probably Walmart too, mine were about
$30, I have two one at each end of the house.
Does Borax count as a chemical? I put it in jar lids in my cabinets when I lived in Texas and it seemed to work.