so, just for grins, lets look at the REAL cost of running a fan on a stove.
If we examine EXACTLY what the wattage turns into, we find that all the electricity to run a fan is converted to heat. Either it moves air (friction turns to heat) or it is "wasted" due to inefficiencies (more heat).
Meanwhile the fan significantly improves the efficiency of a wood stove. The more cooler air you can throw at a hot object, the cooler the hot object will become, and the more air you will warm.
So, pretty simple. Run LOTS of air past your stove if you want to save money.