Hi
What current do you need to drive them, there are different HV step up designs, one fora Nixie can be found at Microchip 170V, 123.microchip.com/download/appnote/pic16/91053a.pdf
I have some links and project but most of them are for the kV range.
TI have one for low current applications, hxyp://focus.ti.com/docs/prod/productfolder.jhtml?genericPartNumber=TL783
Sams schematics (search for link) have a lot of HV designs, perhaps there is some for "only" 100V
Check there and hope it helps you