What is the best way to step up a small voltage, like 3v-12v to 200v? I only need 6mA at 200v, so it is low current, but I am at a loss as to the best way to accomplish this task. I am hoping that you guys can help me narrow down where I look to accomplish this.

I am wanting to make a battery operated display that uses nixie tubes. Ultimately I will need a 5v rail for a microcontroller, a 80v rail for two neon lights and a 200v rail for the nixie tubes. I have built many 5v regulators. But I figure the 80v rail will be the same as the 200v rail in principle.

-edit- Thanks for all the help! This has definitely narrowed my searching down.