(Wines&Vines) - The star investors on ABC’s reality series “Shark Tank” sweetened the pot, but not enough to buy into Copa di Vino, James Martin’s innovative, ready-to-drink (RTD) wine package. In an unprecedented second appearance on the high-rated show, Martin turned down a collective offer from Kevin O’Leary, Robert Herjavec and Mark Cuban of $600,000 for 30% the business. Mulling the offer, Martin phoned his friend and mentor Jim Koch, founder of Sam Adams beer. “He still owns 100% of the voting shares” of his wildly successful brand, Martin said; that weighed heavily in his decision to reject what he termed a “low-ball offer” for a business that’s already growing rapidly, racking up the equivalent of more than 1 million 9-liter cases in just 18 months.