I'm not sure but I think the voltage can be amplified within the monitor to produce 20KV. Why do you need such a high voltage? DO you need more voltage than current? Is there a target watt rating for this project? At 20KV I'd imagine you'll be using a current close to nothing, unless this thing sucks a bunch of energy.

If you want this to be somewhat inexpensive you could try looking for a bunch of broken TV's in a landfill or something and conduct the experiments with the charge left in those. Dangerous stuff though, but that's never stopped anyone .