You can buy bug killers that look like a tennis racket really cheap, I got a couple from the pound store, there is a circuit inside that generates 6kv from batteries, a bit of a heatsink on the trans would make it run for longer periods.
I used a 20n60s5 mosfet to pulse a ignition coil as part of a hf start for a tig welder, it seems to be reliable enough.
Sorry debe, I just realised you allready mentioned tennis racket type bug killers, I didnt mean to steal your thunder.