about $200 if you do it yourself
about $1500 if you take it to a marina. however depending on your insurance, you would only be out the deductable.
just an FYI, the ski ring is for skiing and wake boarding only as it is only rated at a few hundred pounds and attached to one of the weakest points of a hull. (the most force you can put on the ring is a few hundred prior to the rope coming out of your hands.)
tubes need to be pulled from the transom tow hooks with a bridle. they are rated over 4000# each (attached to the strongest point on the hull)
when a tube submarines, it exerts up to 3000# of force and either the rope snaps or it rips the ski hook from the boat.