I'm just looking into the same thing. I'm looking at vinegar dosing though. You need to add more as its less of a carbon source than vodka, but seeing as I can get gallons of the stuff from Costco for $5 then its going to be cheap.
I have also read that people had less of a problem with cyano when using vinegar.
Here's a vinegar article worth reading:
http://reefkeeping.com/joomla/index....arine-aquarium
I haven't started yet so anything I have learned has just been from reading, but I'm always interested in seeing what people think/do.
Following along,
Dunc