I agree with Scott. New foundation, new roof, new walls, permits, blueprint drawings for the building department and you haven't even started on the fixtures.. Kitchen and bath remodels are the most expensive thing you can do in your house with out extending the size, so I think you are probably looking in the $12-15K range. The quickest way to find out is to contact some contractors in your area! I just remodeled my 6' x 8' bathroom, gutted it, extended a wall to put in a shower over the tub, tiled, new tub, vanity, fixures.. did 80% of the work myself and it cost me $5200.