The first challenge would be finding som usable nixie tubes. Judging from various searches, it seems like the most common tubes are the russian made IN-14 or the large IN-18.

The IN-18 looks pretty awesome, but since building nixie based clocks apparently has become quite popular, finding IN-18's for sale with a reasonable price tag seems impossible.

The IN-14's would be fine if it wasn't for the fact the "5" is a "2" mounted upside down, which I don't like.

But then I stumbled upon a package deal with 6 x Z570M tubes on eBay. They have a real "5" and they are coated with a red filter. Perfect.

Upon arrival I wanted to test the tubes by building a HV PSU capable of delivering the 170 VDC neecessary to light the tubes. On the web I found a simple 555-based circuit which I built on a small breadboard PCB.