Michael's (craft supply) has paint for painting glass. I've thought about buying the black paint and seeing how that would work. A way to dip the canning jar into the paint would be ideal. Would have to find larger quantities to be economical. Michael's is about $3 for 2 fl. oz.
For something like a canning jar you wouldn't really need a special paint. A quality latex paint will coat the jar, just need to rough up the surface with some sandpaper( diamond paper if you can find it). Dip it a couple time, allowing it to tack up between coats, and it should be a decently thick coating that should hold up. might need touching up now and then, like any painted thing that gets handled frequently.
There is a type of acid you can get for etching glass which would be good to do before painting, for better adhesion.
You just gave me an idea..I'm going to try sandblasting some jars to frost them, just so you can't easily tell whats in it..thanks!
