American Sci & Surplus is selling 7500v power supplies for $7.75. These
are *AC*, but are sold as "Ionizers" with a needle strip. Perhaps they are
current-limited, but I can't really tell from the description. It's on
the back page of the new catalog, #28701.
Build two of them into a box, each with a 20KV diode in series, for a
pos-neg electrostatic power supply? At these prices you could put one at
every student station in the lab.