It‘s difficult to compare the boat transfer prices, as WA is or will be the only hotel using a big yacht for a shared transfer. Rethi Rah is charging 300++ for a shared yacht transfer(smaller yacht) or 400++ shared seaplane p.p. one way.
Other resorts like Cheval Blanc, Velaa, St.Regis... are offering private transfers with similar yachts, approx. costs 2500-3000 ++ p.hour.