At the time of the 2009 OSTAR the shipping costs for a 33-36' yacht alongside ship to alongside ship, was quoted in the order of £12-£15K for a couple of participants who did ship back, the damage was about £2.5k same as the insurance excess. I think the final cost may have been a bit less, but still a lot.
Most sailed back, 2/3 via the Azores, the remainder straight home. A couple left the boats in Newport RI and went back next year . No idea of the cost. But everything in RI was expensive so I guess storage for 9 months or so would Cost.