Build hand held, high powered infrared lasers to blind opponents silently and invisibly and from further away than they can shoot at you. Faraday cage the basement. Build an EMP generator to disable robots or hidden surveillance devices. Crossbows are handy. Silent. Ammonium nitrate, liquid methane fuel, assuming you know what to do with It. Powdered magnesium, iron oxide, aluminum, sulfur, assuming you know what to do with it. Chemistry set. Chemistry books. Not text books, but how to make medicines and other useful items. Soap. Cough syrup. Etc. Lots of drug store stuff is easy to make.