Need a Small Cheap Power Supply for a Spark Gap

[RJBowman]

Does anyone know of a small cheap battery operated device that produces a current that will bridge a gap of, say, half an inch to an inch. It should be small enough that it could be used as a decorative addition to a prop or costume piece. High voltage/low amperage.

[von Corax]

Marx generator. Search Hack A Day for articles on construction.