That would depend on the type of aircraft they've chartered.  Originally they were using a cessna 206 - a small single engine, relatively cheap airplane.  Now though, and I'm not sure who its surveying for, there is a Dash 7 flying from mcfaulds a long ways east.  This is a large 4 engine aircraft that is much more expensive to operate.  5000/hr is a very rough guess.  Its been there for a couple of weeks now and will probably be there another couple of weeks.  That is major money compared to the original surveying done.