Personally, if it were me, I would just go along side the road, where there is construction, and pick up some stone, either sand stone or slate and put that on the house.
You can get mastic (the type used for z-brick if its for outside useage), or mortar and attach it to the wall, using a sceen type mesh fastened to the wall, then mortar applied and the rocks applied to that. Hold the rocks in place with some tiny nails, until it "sets". Then apply a water proof sealant to guard against moisture getting behind the rocks and busting the entire deal out as it freezes and expands.
This may, or may not save you money, as I'm not sure what you are paying for the "rock sheets" in your area...
Just my two cents worth...