Also note that doing nothing will be a HUGE Problem down the road, as at 60-65% humidity levels you can start to grow black mold, which is thousands of dollars to remove (and potentially causes health problems).
I bought a ~$150 humidifier, that cost ~$10 in electricity a month to keep my basement at 45% or lower humidity. But I get 1200 square feet of basement to use, so a pretty good investment (and much cheaper per square foot than upstairs as the heating and cooling costs are much lower).