I would look to surplus (old analogue) photocopier bias and discharge AC high voltage generator modules. You may be able to locate one that has an acceptable frequency of operation (though they may not be specified or static) and be able to adjust the voltage (usually only safe or practical to adjust it downwards) to suit your application.
These units are not intended or able to provide much current but perhaps your application will still be served.
The thing you may be looking for would look like one of the illustrated boards.
To design one from scratch is not a simple task and would require a lot of research. I saw some pictures of kits and perhaps this would be a middle ground for you as they may be more flexible in specifications.
There are various bits of consumer gear that seem to make use of similar power supplies. One is an ioniser another would be a Neon discharge tube supply.
Images Scientific Instruments may have a possible product and they appear to be adjustable, there are sure to be others.