Michail Papadimitriou over at Electronics Lab designed a simple DC-DC switching regulator capable of powering most of Nixie tubes:
The module is based on the MAX1771 Step-Up DC-DC Controller. This controller works up to 300kHz switching frequency and that allows the usage of miniature surface mount components. It accepts an input voltage from 2 to 16.5V and the output is factory configured to 12V. In this module the output voltage is configured higher at ~180Vdc using external resistors and a potentiometer.
The MAX1771 is driving an external N-channel MOSFET and with the help of the inductor and a fast diode, high voltage is produced.
MOSFET has to be RDSon, Diode has to be fast Mttr, typically < 50nS and capacitors has to be low ESR to have good efficiency.