As you use a 'Gymeatre' or 'theatorium', you will probably have Fluro light fixtures, for general lighting. If you have just buy 'Blacklight/blue' replacement tubes.

Generaly it is cheap enough to pick up some used Fluro fittings, at a salvage yard or where ever. Although these days as most are produced in China, new ones will probably be cheaper?

We normally hang two or three behind the proscenium arch teaser, which gives adequate coverage. If you have a sparkie in your group, they are easy enough to rig a pigtail cable & plug to each fixture.

Or you could hire in a 'UV Cannon' from a theatre lighting company, which are directional & can be focused on to specific areas.

A few things to remember is white under clothing will show up, especially bras, falsies & panties. So they may have to wear some scraggy old flesh coloured underwear ones. Also dandruff shows up amasingly, so get them to use 'Head & Shoulders, to avoid this especially on black clothing. {Washing powder flakes will also fluoresce}