Demolition of house

Is there a posting on here or someone on here that has dealt with tearing down a house? How much is the cost per square foot to do so. Today i have found an reo bank owned property listed in my area. However the problem is that it has ad a fire and is not habitable. It has also been rezoned to commercial from residential. I am considering making an offer on this property however since i am not sure how much it would cost to demolish the house i can not make a proper offer. Bassically it is only worth the amount of the land since the house is worthless. I know that i have to lower my offer by what it would take to tare the house down. Is any one on here a commercial developer that could shed some light on this for me?