You can get kits from here:
http://www.arduinix.com/for the actual nixie tubes and the controller.
For the back end, you will need to pull data from an API from one of the block explorers and have the audrino push it to the tubes.
If you don't know programming or how to setup an arduino then it is a massive undertaking.
However, if you want to use an LCD with a RPi then there are a few open source price tickers available.
Since all you want is the number of blocks it's probably easier to build one of those and just hack the display code a bit to just display the block count.
-Dave