Alternative Heaters

Delicious warmth...
Delicious warmth...

My ugly-ass heater is broken, and it's supposed to get down to 9 degrees tonight. In it's place I'm using the oven to heat my small apartment. It's pretty effective, actually, and an incinerated crumb smell has taken the place of the incinerated dust smell. But the question arises--which is the more expensive heating mechanism: the actual heater or the oven?