Not sure if anyone can answer that one Tracey,havnt seen the post you refer to.I dont understand how its feasible to work out the cost of this as it would depend on the amount of hours run.Then if you are on a digital meter what times it was run and if you were running it for summer cooling or winter heat.Also the size of the unit would have to be taken into consideration.I think you need an electrician to work out the watts of the unit to calculate power used and subsequently the times of usage for unit cost.I hope that all makes sense regards J