I just use elec tape in the front, and a vinyl cap I snagged at work for the rear.
You can actually get free samples of caps if you want and have some "business interest" ;)
The one I have is flanged, but I'm going to get a regular short cap in vinyl. It fits tight, and at worst a drop of CA holds it on. Poke holes for the wires and it will help retain the cap further and seal up tight. Nice as it keeps bearings clean