UV Photography

[Trevor Cunningham <trevor@xxxxxxxxxxxxxxxx>]

I've been working with IR images for some time now and could probably 
use a break (unless I find some really cool plants). However, I was 
reading the February edition of NatGeo and read the article on feathers 
and birds' prehistoric ancestors. Robert Clark did the photography (and 
the images are amazing). On the next to last page of the issue, in one 
of their behind the scenes vignettes, is a picture of Robert Clark 
taking UV images of a parrot. I sent him an email asking about his rig 
and he detailed the components:

Broncolor UV-only strobe adapters: ~$1200 a pop from B&H, and he had 
three (the adapters are designed to fit the $3K Broncolor Pulso flash 
heads)...a little out of my price range, but he did indicate they were 
very expensive
Nikon D-70: Apparently, it has a special UV setting...I would think my 
fixed IR-only filter would interfere with UV, but I could be wrong.
Lens (unknown make): Obtained from the FBI and all elements free of UV 
coating.

A little ground searching turned up mention of the Nikon SB-140 flash 
unit (no longer in production), or a combination of SB-14 and SW-5UV 
parts to produce a makeshift UV flash unit. What glass considerations 
are required here? Can anyone think of another affordable option?