Hi Diana,
I have only use an asymmetric with a crew member aboard, but I have seen single handers use them with a sock it light breezes. There are a bunch of places that sell stock sizes so they are not too expensive ( about $800) for a small boat like a Top Hat. You would only use it in light winds, but it could get a bit exciting if the wind came up quickly and you had to get it down on your own. They are pretty big. The one I bought is actually bigger than the my symmetric spinnaker ( though my symmetric it is a heavy weather kite).
I would suggest you have a sail on a yacht with an asymmetric and a sock and see how easy/hard it is to use. I do not use a sock because I usually have a slave on board, but you would definitely need a sock for single handing.
Regards,
Mark