It's doubtful you will really be able to machine metals (with the possible exception of aluminum) effectively on your home-made gantry mill, so concentrating on a spindle that can cut wood makes most sense. Those Chinese 2.2KW spindles are designed to run on 220v; are you sure there isn't a dryer or stove circuit you can use? Otherwise you're stuck with a regular router, unless you want to rig up your own spindle assembly.