In my previous house I left my blower on ALL the time, for the sole purpose of moving the air around. The house was in a subdivision and as such, opening the windows did not move the air around too much.
My Hydro Company has an appliance calculator with a list of the common appliances. It has 2 options for the Furnace Fan Motor; intermittent operation and continuous
For the intermittent operation, the default settings are 5 cents/kWh, Power used 0.4 kW, 10 hrs a day for 30 days, which works out to $12.56 a month.
For continuous operation, the only real change is 24 hours a day, for a monthly total of $30.15.
The difference is $17.59/month, or $211.08 a year.
these are obviously averages (well, the 10 hrs per day is for sure), but it does add up, not too mention the lower life expectancy of running a motor all the time.
so it truly is, just money