Cablevision Chairman James Dolan said last week that any buyer of its coveted cable systems would likely have to pay what he described as a price never seen before by the industry. Mr. Dolan addressed the possible sale of the Bethpage, N.Y.-based cable system during a UBS Securities investor conference in New York. However, he added: “Clearly there is a great deal of upside in this business … [which] would require a valuation that we’ve not seen before. For someone who’s hungry, it would be a rather large bite.”