Yes, I would do it for free. As kids, my friends and I would walk to a graveyard and play hide and go seek. We would think it was cool when we'd come across an open grave. I guess I have been ok with morbid stuff since I was little. Makes during my current job entertaining.
Never had an encounter with a spirit, even in buildings reported to be haunted but I suppose they could exist. I'd do it, if only to see what came of it (the $10k wouldn't hurt, either). Besides, hauntings aren't all supposed to be bad, are they?