A quick googling suggests it's probably in the $10-20 range, though there's obviously variance in how often you run a load, and electricity costs in your area.

A quick googling suggests it's probably in the $10-20 range, though there's obviously variance in how often you run a load, and electricity costs in your area. Not literally "a few" in the sense of like three or four bucks, but a very small price compared to the dozens of hours of labor you're saving each year.