The cost of a piece of metal in your eye.

Also, don't forget to wear goggles when using fluids of any kind. I was using some acetone to clean a greasy part and splashed some in my eyes. I was blinded for about 5 minutes and my eyesight was blurry for a few hours.
Oh, and this is from a professional chemist who thought that a little bit of solvent wasn't going to go anywhere so I kept my goggles on my forehead.